As of March 2017, we are using a new USB license key. This new key requires NO Windows Driver, it utilises a HID interface, Windows natively supports the device without third party drivers.

At this time it might be worth a mention that we look favorably upon requests for a second - Backup - License key.

Users that have purchased proton Compiler are able to purchase a backup key, in case they loose the original or the original becomes faulty leaving them unable to compile, whilst awaiting a replacement.
The replacement key service, can be used to order a Backup key

Same rules apply, 1 replacement per user.

So you have the flexibility, you either wait until you need it, or you can order in advance and look after the spare key yourself. I hope that users feel that this is a good solution to the lost / broken key issue.