The Activation Key is used to activate Stitchmastery 3 so that it runs in full mode rather than demo mode. The Activation Key can be used on two computers, and at the moment gives lifetime access and free upgrades. Future upgrades may incur a further cost. The payment options are credit/debit card via Stripe or PayPal.
If you do not already have a copy of the Stitchmastery software, download it from https://www.stitchmastery.com/downloads. It can be used on Windows, macOS and Linux systems. Once installed it will run in demo mode until activated with an Activation Key.