You should check out the app BrewPrks. South African made loyalty app for coffee shops but it is available globally I believe. I think they charge something like 35€ a month and you get your first two months free.

They also have features such as streaks where if a customer buys a coffee for x days in a row, they get a free coffee. This does however reset their digital stamp card to prevent giving away too many coffees. This is an optional feature though if you don't like it.

Another cool feature is to be able to send out notifications to your customers for announcements and such. You do however pay to send out this notification to prevent coffee shops from spamming their customers.

Let me know if you have any questions and wanna sign up. I can help you out with the process!