You can collect stamps on your stamp card by making a purchase in the game. For each purchase, you will get one stamp. Fill out your stamp card to get a reward!
Any purchase will grant a stamp.
When visiting the shop, the stamp card and the number of stamps completed will be visible at the right side of the game screen.
Once the stamp card is completed, a button will appear to claim the reward.
Stamp cards have one use only and it will disappear after completing it.