I think it’s a clever hack that they issue you a ”free coffee” coupon once an hour. It’s also great they have built their app to be flexible enough to support such changes and communicate about them without needing an update.
That’s something I always try to remind app owners as well: that operations are crucial for your success and you should design and build your app in a way you are flexible to experiment with new ideas.
Some tools are: flexible push and in-app notifications, minimising client-side business logic, flexible localisation setup, possibility to integrate web content on the fly inside your app. In this case, it’s also about leveraging an existing, frictionless payment with a stored credit card. (By Nets Group in this case.)
(It was said in the news that Espresso House is the first to do this in Finland but didn’t Cafe Picnic have something similar earlier?)