A licence key
the thing you send after they payA short code, something like ACME-4K2P-8ZQD. Your customer
types it into your program once. Until they do, the paid parts of your program do not
open.
Licence Keys for Your Software
Fox Licensing
Sell your software. Keep control of it.
Sell one Windows program as a free trial, a one-time purchase, a subscription or a basic version with paid extras, and stop one paid copy running on ten computers. A licence key tells your program exactly what it may do, and you can see where each copy runs, move it, or switch it off.
ACME-4K2P-8ZQD-1R7M-VN3S-HTB
Runs on 1 computer
Stops after 30 days
You charge nothing
Runs on 3 computers
Stops after never
You charge once
Shared by 5 at a time
Renews monthly
You charge every month
Adds to a licence they own
Lasts as long as that one
You charge for the extras
Same program — the key decides
- Viewer
- Measurement
- Reporting
- Batch export
- Advanced analytics
- Automation
Let them try it for a month on one computer. The expensive parts stay switched off — the program they downloaded simply never opens them.
They pay once and it never expires, on up to three of their computers. Batch export is included; the two heavier tools are sold separately.
They pay monthly, and the renewal happens by itself in the background. Five people can use it at a time — whoever opens it first.
They already own the basic version and now buy the extras. Everything switches on where it is — no new key to install, nothing to download again.
Working · 22 days left · keeps working for 3 days without internet
Working · never expires · 2 of their 3 computers used so far
Working · renews on its own · the slot frees up when they close it
Working · added on top of the licence they already had
Press the four buttons. The licence key is invented, but everything that changes underneath is what the product really does.
In Plain Words
If You Have Never Bought Licensing Before
Software licensing has its own vocabulary, and none of it is obvious. Here is the whole of it in six sentences. Everything further down this page is built out of these ideas.
Turning it on
activationThe moment their computer checks that key and gets permission to run. It takes a second and happens once — after that your program remembers, and quietly confirms in the background from time to time.
Tied to one computer
node-lockedThe licence works on that machine and no other. Copy the program to a second computer and it will not run there — which is exactly what stops one paid copy becoming ten.
Shared across a team
floating, or concurrentInstead of naming computers, you sell a number. Buy five and any five people can be using the program at the same time; when one closes it, the next person gets their turn. Thirty engineers, five licences, nobody administering it.
Computers with no internet
air-gappedPlenty of industrial and defence machines are kept off the network deliberately. They are licensed by carrying two small files across on a USB stick — one out, one back — and it works exactly as well.
Switching one off
revokingA licence you cancel stops working, and stays stopped even if the customer reinstalls, restarts, or unplugs the network. Useful when an invoice goes unpaid or a laptop walks out of the building.
Ways to Charge
Four Ways to Sell the Same Program
You build and ship one thing. Which of these four a customer gets is decided when you issue their key, not when you build — so adding a subscription option, or a cheaper trial, costs you nothing in development.
Let them try it, safely
Runs for as long as you decide, usually on one computer, with the parts you would rather not give away left switched off.
- Stops on a date, not on trust
- Expensive features can be held back
- Becomes a paid licence without reinstalling
They pay once and keep it
The ordinary sale. It never expires, and you decide how many of their computers it covers.
- No renewal date to explain to anyone
- The computer count is enforced, not assumed
- A licence can be moved to a replacement machine
Renews without a phone call
Shortly before it runs out, the licence quietly extends itself. Your customer does nothing and notices nothing.
- Nobody re-types a key on renewal day
- Stop the subscription and it lapses on its own
- Money every month without anyone chasing it
Sell an extra, not a new version
A second, smaller licence that adds features to the one your customer already bought.
- Sell more to the same customer, with nothing to ship
- You name the extras; the licence lists them
- Switches on within the hour, by itself
Inside your program this is one line of work. It asks whether this customer's licence includes a named feature, and switches that part of the screen on or off accordingly. Your developers write no licence checking, no expiry dates, no key handling — those live in the licensing system, which is the point of buying one.
Naming Computers, or Counting People
Sell Five Licences to a Team of Thirty
Rather than listing which computers may run your program, you sell a number of slots. Whoever opens it takes one; when they close it, the next person gets it. Nobody has to manage that, and your customer stops arguing about how many copies they need.
WS-004
In use
WS-011
In use
WS-014
In use
—
Open
—
Open
WS-014 took a slot at 09:14 and is holding it while the program is open. Try either button and watch the count.
Or tie it to one machine instead
The other way round: the licence is locked to a single computer, recognised by its own hardware. Install the program somewhere else and it will not run there — it says this is a different machine and waits for you to approve the move.
That is the right choice for a machine you sold, a controller on a factory floor, or anything that will never reach your server. Air-gapped activation is node-locked only — counting shared slots needs a server to count them, so a licence cannot be both shared and offline.
Your program does not have to know which kind it is. You choose per customer when you issue the licence, and nothing in your software changes.
The panel above is a drawing of how this really works, not a live connection to a licensing server.
Machines With No Internet
Licensing a Computer That Is Not Online
Plenty of the machines worth licensing will never see the internet — a controller in a plant, an inspection workstation on an isolated network, anything inside a defence installation. A USB stick and two minutes, and that machine is licensed properly.
01
.c2v
The machine asks
Your application writes a request file on the offline machine. It carries that machine's fingerprint and nothing a customer needs to understand.
02
.v2c
You answer, signed
Upload the request in the console, choose the customer and the licence terms, and download the signed response.
“A customer with an air-gapped machine sends you a .c2v
file. Upload it, choose the customer and license terms, and download the signed
.v2c.”
03
.c2r
And you can take it back
When the licence has to move to another machine, the offline machine produces a receipt. Upload that and the seat is free again — the transfer is auditable in both directions.
The response only works on the machine that asked for it.
The .v2c is an authenticated envelope sealed to that machine's
fingerprint, so a customer who copies it to a second machine does not get a second licence —
they get a failed authentication tag. This is the part a hand-rolled licence file almost never
gets right.
Every Case, Already Handled
What Happens When Something Goes Wrong
This is where a bought licensing system earns its money. Eight situations, each one already thought through, so your software behaves sensibly instead of guessing — including the awkward ones, like an engineer whose laptop has been off the network for two days.
No licence yet
ActivationRequired- What happened
- Fresh install, nobody has typed a key.
- Your software
- Asks for the key. The paid parts stay shut.
Everything is fine
Active- What happened
- Paid, current, confirmed recently.
- Your software
- Runs, with whatever they bought switched on.
Been offline a while
Grace- What happened
- No internet for a few days — a site visit, a hotel, a plant.
- Your software
- Keeps working. A dead connection is not a licence problem.
It ran out
Expired- What happened
- The trial ended, or a subscription was not renewed.
- Your software
- Stops the paid work and offers to renew.
Different computer
HardwareMismatch- What happened
- The licence was copied to another machine.
- Your software
- Will not run, and asks you to approve the move.
You cancelled it
Revoked- What happened
- Unpaid invoice, ended contract, a laptop that left.
- Your software
- Will not run. Restarting does not bring it back.
Someone moved the clock
TamperSuspected- What happened
- The date was set back to stretch a trial, or the whole machine was rewound to an older copy of itself.
- Your software
- Will not run, and you can see the reason.
The licence file broke
Corrupt- What happened
- A disk problem or a bad shutdown damaged it.
- Your software
- Repairs itself from a spare copy; if all are gone, asks for the key again.
Filled dot: your software runs. Hollow dot: it stops, and it can say exactly why. The small grey line on each card is the name your developers will see in the code. How often it checks in, and how long it keeps working offline, are yours to set.
What It Resists
Written for Someone Who Will Try
Anyone can compare a string to a key. The interesting cases are the copied licence file, the clock set back a year, the rolled-back virtual machine, and the licence that has been revoked but keeps working because the software forgot.
Your program never holds the licence itself
A separate Windows background service holds it, and your program only ever asks it questions and gets yes or no back — never the licence, never the secret. Someone pulling your program apart to strip the licence check out of it finds nothing to strip, because the decision was never made in there.
Nobody can listen in, or pretend to be you
HTTPS with SPKI SHA-256 certificate pinning that cannot be overridden at
runtime, so a proxy with a trusted root does not get to listen. Each product authenticates
with its own HMAC-SHA256 secret.
An offline licence only fits one machine
X25519 key agreement with ChaCha20-Poly1305 authenticated
encryption. The response is bound to the requesting machine's fingerprint — elsewhere it
fails the tag check rather than degrading quietly.
Turning the clock back buys nothing
Every check writes to a rollback ledger. A system clock set back, or an update counter that
decreases because a virtual machine was restored from a snapshot, produces
TamperSuspected — the two oldest tricks in the trade.
Cancel one and it stays cancelled
Revoke a licence and it stays revoked through restarts, reinstalls and time offline, because the decision is recorded in the machine's own encrypted ledger rather than depending on the next successful server call.
The licence cannot be edited on their disk
Encrypted on disk with a SYSTEM-only ACL; vendor codes are writable by
administrators alone. A damaged store recovers automatically from up to three rotated
encrypted backups.
Swapped files get noticed
Every shipped file is listed in a SHA-256 manifest, so a swapped DLL is a
detectable event and not a mystery support ticket.
Integration
It Fits Into the Installer You Already Ship
Licensing arrives as a small Windows background service plus two files that sit beside your program. Nothing about how you deliver your software changes — your installer gains one step, and there are four ways to add it.
Run the MSI
Installs the service, sets the permissions and starts it. On upgrade it stops the old service, replaces the files and restarts.
Manual install
Copy the service\ folder and run it once with
--install. For a developer box or a CI runner.
WiX Toolset
For teams whose product already ships as a WiX-authored MSI or bundle. The complete XML is in the manual.
InstallShield
For products whose shipping installer is an InstallShield project, with the click-path documented step by step.
Targets net481
Targets net8.0
Or anything netstandard2.0
Host OS Windows
The manual is part of what you get
Fourteen sections written for whoever does the work, including the one that matters on a bad afternoon: every error message your team could hit, listed word for word with what to do about it. Downloadable, and it prints.
- Three installer paths, with complete WiX XML
- Vendor codes, and how to rotate them
- The state machine, and the behaviour for each state
- Online, offline and reactivation flows end to end
- Feature gating, revocation and SKU configuration
- File formats and an API cheat sheet
How You Buy It
Own the Platform, or Let Us Run It
Most product companies want their revenue protected. Very few want to operate a licensing back office to get it.
We run it
We build it in, and we run it
We add licensing to your software and operate activation, seats, renewals and revocation on your behalf. You get the console access you need and none of the responsibility for keeping a licensing service alive.
- Integration into your existing installer and code
- We issue, renew and revoke on your instruction
- Air-gapped exchanges handled for your field customers
- No licensing infrastructure of your own to maintain
You run it
Take the whole platform
The licensing system itself, running under your control, with your own team issuing licences and managing seats. For companies that need licensing to be theirs — because of a procurement rule, a data-residency requirement, or simply preference.
- Admin console, API, SDK and Windows service
- Your products, your customers, your database
- Team accounts with group-based access
- Handover with the full developer manual
Tell Us What You Ship
What the product is, how it is installed today, and how you would like to sell it — trials, subscriptions, modules, concurrent seats, or machines that never see a network. We will tell you what the integration looks like in your codebase before anyone signs anything.