Stampit app was build to replace current paper version of loyalty cards, which are easy to lose, or they are just being used as bookmarks. In the app, you can add them in digitalize version, where they look the same as the current paper version.

Adding stamps is done with help of NFC. You will just visit a store with the Stampit loyalty program, hold your digital loyalty card near by the store's little wooden box that holds NFC tag, and after a very short moment, you will have another stamp on your card.
When you collect enough stamps at the store, you can redeem your coupon the same way you collect the stamps. You click the "Redeem coupon", place your phone neer by the store's NFC box, and after a moment of verification, you will get the valid coupon that you can use to staff and enjoy the reward four your loyalty.

Simple, fact, and eco.