You may have "used" a license without realizing there was a license already in use. It is possible to use more than one license. First, release all licenses, close Altium and then re-open Altium to see if that resolves the issue. There are other reasons this can happen. This issue could be related to License Allocation Assignments. If you have multiple licenses, and more than one of them is set to "Automatic leasing" in the Options section of a License Allocation assignment, try unchecking this check box for all allocation assignments. If you have created a license allocation assignment that includes multiple licenses, try removing this assignment and set up individual assignments for each license. Make sure the total number of seats allocated for all the license allocation assignments does not exceed the total number of seats available for the license. It is also important that a user is not included in more than one group such that the allocations result in the user seeing the same license twice in their License Management screen. Here is documentation that should refresh your recollection on working with allocations (let us know if you need help with this): On-Demand type: https://www.altium.com/documentation/altium-designer/altium-dashboard-managing-licenses#license-allocation Private Server type: https://www.altium.com/documentation/altium-infrastructure-server/private-license-service#!license-assignments This issue could be related to already using a license on a different computer. You are able to release your own license remotely from their current session. This documentation should help: https://www.altium.com/documentation/altium-designer/on-demand-licensing#!releasing-a-license-remotely This issue could be related to the computer having multiple active network adapters. Try disabling any unneeded network adapters. Although written for a different purpose, this Knowledge Base article has a good description (with images) on how to do this: https://www.altium.com/documentation/knowledge-base/altium-designer/nothing-happens-when-trying-to-use-a-license If you are using a private license server, this issue could be related to having more than one account for the user on the issuing server. This is especially true if you manually created an account on the server and also have the server set (default) to automatic user creation. If your server is using this default, you can delete the user's accounts and let a new on be created when they attempt to re-connect.