All the costs are added to the card* which you used to register. You can use a Bancontact & Payconiq, a normal credit card as VISA, Mastercard or American Express card as well.
You can check the overview of your trip via the app in : Account > Invoices. You will also receive an automatic e-mail with the estimated costs at the end of your trip. 💶
You can easily modify your credit card via the app. ⬇️