Had a situation recently when building a 2012 R2 RDS farm that the message
“Licensing mode for the Remote Desktop Session Host is not configured”
kept appearing, even though the licensing server was activated etc. and the server was configured to use it.
Thankfully, this site had the answer
$obj = gwmi -namespace “Root/CIMV2/TerminalServices” Win32_TerminalServiceSetting
$obj. SetSpecifiedLicenseServerList(“licserver.domain.local”)
HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server\RCM\Licensing Core\LicensingMode
Change the DWORD to 2 for Per Device or 4 for Per User
Update 6/09/2016
An employee mentioned to me that setting the license server and licensing mode via group policy also seems to get around this bug
Computer Policy\Computer Configuration\Administrative Templates\Windows Components\Remote Desktop Services\Remote Desktop Session Host