Software license key system: how it works and how to set one up

What a license key system does

A license key system is the part of your software business that decides who is allowed to run what. It creates keys, remembers which customer and which computer each key belongs to, answers “is this key valid right now?”, and lets you take a key away or extend it when things change — a refund, a leak, a renewal.

Without one, a single purchased key ends up on a forum within a week. With one, the key only ever works on the computer it was activated on, and you can see when that changes.

How Foliox License works

1. Create a product and generate keys in your dashboard — one at a time or hundreds at once, with a fixed expiry date or “N days after activation”.
2. Your app asks the API to activate the key on first run and verify it on every run after. The first device to activate wins; any other device is refused.
3. Every answer is signed with Ed25519, so your app can verify it offline and a fake server can’t say “yes”.
4. You stay in control: revoke, restore, extend or reset a device from the dashboard, or through the API from your store.

Built for developers who sell their own tools

• Device locking with admin-approved device resets (customers can ask for one themselves).
• Offline grace — the SDKs keep your app running for up to 72 hours if the service is unreachable.
• Customer e-mails — the key on creation, a reminder two days before expiry, and a notice when it ends.
• Google, Discord or e-mail sign-in and two-factor authentication for your account.
• A free plan that includes all of the above, with room for real projects.