License mismatch is a known issue with the license administration module.
The Allocation Tab is corresponds to the info in the Current License, while the Assignment Tab is corresponds to the info from all installed licenses.
Refer SAP note 2385934, the error has been recorded and is a candidate to be fixed in a future version.
2385934 - License Assignment Screen Shows Incorrect Information
951816 - No License Available in License Allocation
In case you have some user without license, the process mentioned on the Note 951816 will liberate all licenses to be reassigned.
951816 - No license available in License Allocation & 2385934 - License Assignment Screen Shows Incorrect Information
Workaround:
1. Close all SAP Business One clients.
2. Make a copy of the B1Upf.xml file and save it with a different name or in a different folder.
3. Delete the original B1Upf.xml file.
4. Stop and restart the license server , Restart the "SAP Business One Service Tools Service" from Windows->Services
5. Connect to SAP Business One client and reassign licenses for all users under Administration → License → License Administration.
The location of SAP license file is in C:\Program Files (x86)\SAP\SAP Business One ServerTools\LicenseHTTPS\webapps\lib