Surely you've seen the "punch cards" at your local sandwich shop... Each time you come in for lunch, they punch your card. On the 10th punch, you get a free sandwich? Well- we can provide you with that exact same capability right through your app, but don't be mistaken and think it's just for sandwiches.
With a little imagination, you can use this function for event attendance, number of times they've come into your retail store, etc.
You can also award the users more "points" for leaving location services and push notifications enabled!