In some situations it is possible that you are missing a license to assign to a user. This might happen if you are working in a test administration where you created a test user and assigned a license to this user. If you then delete the test administration or replace it with a new backup of your live administration, the license is gone. The only way to resolve this is this procedure:
Log in to the server where the Licensemanager is running and stop the license service. Then open the folder C:\Program Files\SAP\SAP Business One ServerTools\License. Copy the B1LicenseFilexxxxxx.txt to your desktop or any other folder you have access to. Then delete the following files:
Start the license service again and import the licensefile you have backed up to your desktop. After that you will have all licenses available again and you will have to assign them again to your users as they are all reset by this procedure.