It may happen that the message 'The maximum number of users for this license has been reached' is displayed in XL-ENZ.
When this message is displayed, navigate to the menu: Main menu | System Management User Management | User Information
Here you can see a list of active sessions. Assess which session can possibly be closed (this can be an old session). Select the user and the 'Close session' action for the 'selected' user. Then choose 'Run'
This concludes the session and an additional license is available with which you can log in.