When am i old enough to stay alone in hotel room?

Depends: Are you talking about staying by yourself in your parents' hotel room for part of the evening while they go out, or renting a hotel room all by yourself? If parents' hotel room, it is their decision, based on their impression of how mature & responsible your behavior is, and how safe the hotel is. To rent a hotel room by yourself, you usually have to be at least 18 and show id to prove it.