Finding a Remote Desktop Services (RDS) "license key" typically depends on the licensing program you used for the purchase. For most modern enterprise volume licenses, a traditional 25-character product key does not exist; instead, you use an Authorization Number and a License/Agreement Number to activate the licenses on your server. Where to Find Your Licensing Information
If the server crashed and you have no backup of the Licensing Server, but you know you bought licenses, you must perform a License Key Pack ID Recovery. how to find rds license key
You will need your original Microsoft Agreement Number (e.g., 0000000 - 7 digits for Open License). Finding a Remote Desktop Services (RDS) "license key"
