Coffee Kiosk loyalty card app

I need to a make a simple Loyalty card app for both Android and IOS. When a customer comes to buy a cup of coffee, The customer can scan a unique QR code which is with the barista. Once the QR code is scanned by the customer. The code get linked to the purchase and it cannot be used again. A new QR code will be generated for the next customer. Once the customer scans the code, The app would show a simple Loyal card indicating that he has bought 1/8 cups and the 9th cup is free for example. The App should allow the kiosk owner to have several loyalty card options. For example - Th Kiosk would give a certain group of people a loyalty card giving a free cup of coffee if the buy 4 cups. Another group might need to buy 8 cups to get 1 free. The app should give the kiosk owner the flexibility to change it as they please. Also the app should send notification to the customers about special events or offers etc.