This is easy!
Every Player object has a property called "Membership Type" that denotes what level of membership a player has.
If this area features a touch door, you'd likely want to use :GetPlayerFromCharacter() to find the player, and then .MembershipType to go from there.
You'll have to use a MembershipType Enum though when checking it with logic statements like "if/then".
Search for "membershipType" on this page under "properties", and click on it:
http://wiki.roblox.com/index.php?title=API:Class/Player
Also, looking through the Class Reference on the Wiki will show you tons of stuff you can do with Roblox objects you might not have originally thought possible. I recommend doing some exploring!
Hope this helped!