You could charge money for the app. If your app doesn't require lots of people to be on it, then selling it might be the best bet. Then your app is only used by

You could charge money for the app. If your app doesn't require lots of people to be on it, then selling it might be the best bet. Then your app is only used by people who really want it. This gives you less support time and a user base that's really enthusiastic about what you have.