This means you could openthe account, stick the card in a drawer, and not even think about it again until you want to close your account (once your credit has improved) and get your deposit back.
When a card was inserted into the tabulating machine, the counters would be updated accordingly, and the appropriate drawer in the sorting machine would open.
If she's currently employed at another nearby hotel, check into the hotel where she now works for a night, run your fingers along the top of the picture frames checking for dust, open every drawer and cupboard in every piece of furniture in the room, and spend several minutes crawling around in the floor in your room looking under things.