Whenever you want to e.g. redeem a ticket for event admission or collect a food item using a food voucher, simply click on the selected items in order to activate them. The issuing merchant can then scan your QR-code and approve the admission or your order.
Do you have additional questions? Check our knowledge-base here https://centi.ch/faq/knowledge-base. We are happy to help you with additional questions and you can reach us under support@centi.ch!