What if someone picks my logo for their restaurant?

A friend is opening a restaurant. He offered $100 to whoever came up with the best logo. If he picks mine, am I entitled to anything else? It would be my creation so I would feel the need to make sure it stays mine, but I would be okay with it being used for the restaurant. Hypothetically, if the restaurant became a chain and the logo was used multiple times, wouldn't I be entitled to more money? (I don't think the restaurant will become a chain, this is part of the question is more for my own curiousity.) Thoughts?