This will fix the following error assuming you have a configured terminal server license server on the network:

"The remote session was disconnected because there are no Remote Desktop License Servers available to provide a license"

The graphical management tools for RDS Session Host Management are disabled when not oprerating a Domain (why?). The fall back is configuration via group policy:

Local Computer Policy -> Computer Configuration -> Administrative Templates -> Windows Components -> Remote Desktop Services -> Remote Desktop Session Host -> Licensing
Use the specified RD license servers = <server IP>
Set the Remote Desktop licensing mode = Per User

This got us to a stage where Licensing diagnostics looked good and no related local errors showed up in the server logs but remote sessions were still refused, leading to...

2.  Force-removing the RDS licensing time-bomb registry entry:

computer\hkey_local_machine\system\CurrentControlSet\Control\Terminal Server\RCM\GracePeriod

RegEdit alone couldn't do it. It had to actually be run under highest privileges with the help of Sysinternals: psexec -s -i regedit.exe

After another reboot things seem to be working now