The license key is a static file which, upon uploading, allows GitLab Enterprise Edition to utilize paid features. During license upload we check that the active users on your GitLab Enterprise Edition instance doesn't exceed the new number of users. During the licensed period you may add as many users as you want. The license key will expire after one year for GitLab subscribers. As of 2022, license keys are a legacy method to activate GitLab paid plans and have been substituted by an Activation Code for most paid subscriptions.