When we stayed at BLT, our keys did not get us to the lounge We had to go to the lobby (at BLT) and they (lounge employees) would take you to the elevator, then scan THEIR card.
They never asked to see the resort ID or anything. We could have been non-
DVC, DVC staying at a different hotel or just Joe off the street. I am not real sure that they care.
Lounge was great though. Time to open it for all DVC guests!