The chains have an app. You have a jar of stamps. Tenth puts your shop's loyalty card into Apple Wallet and Google Wallet. Customers scan the code on your counter and the card is on their phone - no app, no sign-up, no email. Staff stamp it from any phone or tablet. You get the part paper never had: who came back, who went quiet, and how many free coffees you owe. Free to your first 30 customers, then £29/month.