The expiring date correspond to your demo license (quantum_15.0.lic) which is automaticlay generated at the first startupof VNL 2015.0.
This license is read before the floating license and, since it is a valid license, VNL starts with no problem.
If you really want to test that your server license is working correctly, try to remove the file above. VNL should now try to checkout the license loaded in by the license server.