The first time the client connects to the server via RDP, it is issued a temporary license for 90 days, if at the end of the term there are no free installed client licenses, we will receive the error "The remote session is disconnected due to the lack of available terminal server client licenses for this computer." To get a temporary license again, on the client computer, you need to delete the HKEY_LOCAL_MACHINE\Software\Microsoft\MSLicensing branch in the registry editor or using the command line:
reg delete HKLM\SOFTWARE\Microsoft\MSLicensing\ /f
After deletion, the first connection to the remote desktop must be performed on behalf of the administrator in order to get the rights to create a new registry branch with information about the license
