To find out if you are using a Mac-only license account, from the Mac app, you can head to Preferences → Account.
It is important to note that to register your device with a Mac-only license, you would have to enter your license key, starting with SK3. Our subscription-based model uses an email/password combination to complete the sign-in to the Mac app.
If you are currently using a Mac-only license account, you’ll see a screen similar to this one in the Account window:
If you are already using Sketch with a subscription, you’ll see a screen similar to this one in the Account window:
If you are unsure, please get in touch with us and our support team will help confirm.