The remote session was disconnected because there are no remote desktop licence servers available to provide a licence

For some unknown reason a server with Remote Desktop working with Licenses installed will stop accepting connections with the error:

The resolution is to take ownership of  and delete the key

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server\RCM\GracePeriod

Then after a reboot, connections should work as they did previously.