liu but you are running Rhino as administrator? (right-click on the Rhino icon)
It should always inform with a popup "Elevated privileges..." when you enter the RN options page and you're not in admin mode. This is a safety check to prevent employees from messing around with the licenses, especially in bigger office environments.
So make sure you are running Rhino as admin first. If this doesn't help let me know by reporting a bug related to UI and leaving info that will help me to track this issue.