Add RDS License Servers

$obj = gwmi -namespace "Root/CIMV2/TerminalServices" Win32_TerminalServiceSetting
$obj.ChangeMode(4)       >>>>   Note. Enter 4 if the server must use Per User licensing type, and 2, if it is Per Device.
$obj.SetSpecifiedLicenseServerList("EXAMPLE-SERVER_NAME.domain.local")
And check the current settings:
$obj.GetSpecifiedLicenseServerList()