redemption points or stamp function.

Hi, 

I operate a small cafe. So i was thinking if i got 1 customers who buy 10 drink from me over a period of time, i can reward him with 1 free drinks instead.

Method of implementation, could be. every time he buy 1 drink, i will let him use the camera app to scan a QR code for example, and it's stored inside the app. Once 10 stamps is redemped, 1 free drink.

Workable?

Thanks.