post https://keyauth.win/api/1.2/?type=upgrade&username=&key=&sessionid=&name=&ownerid=
Assigns an unused license to a user
Do not log the user in after a successful upgrade, the upgrade endpoint is simply for a user to activate a key on their account. There's no password verification, so it would be unsafe for you to log the user in because all the user needs is an account username and valid key.
Code Example
KeyAuthApp.upgrade(username, key);