Configure RD Licensing Server

$obj = gwmi -namespace "Root/CIMV2/TerminalServices" Win32_TerminalServiceSetting
$obj.SetSpecifiedLicenseServerList("Your Licensing Server FQDN")

Verify RD Licensing Server Configuration

$obj = gwmi -namespace "Root/CIMV2/TerminalServices" Win32_TerminalServiceSetting
$obj.GetSpecifiedLicenseServerList()

Change Licensing Mode

$obj = gwmi -namespace "Root/CIMV2/TerminalServices" Win32_TerminalServiceSetting
$obj.ChangeMode(value)

PS: Value = 2(Per Device)/4(Per User)

Verify Licensing Mode

$obj = gwmi -namespace "Root/CIMV2/TerminalServices" Win32_TerminalServiceSetting
$obj.LicensingType
$obj.LicensingName