Credit Card only?

I would like to buy a cross-plattform key but I can’t since I don’t have a credit card. I think it’s not very customer friendly to offer credit card only in the year 2022. I know that I could buy premium through AppStore, but it doesn’t help me if I want to use the app cross-platform. Maybe think about the option of including a cross-platform license in the AppStore or just offer Paypal payment on the site.

You are right, the only payment options are Visa and Mastercard. When it comes to PayPal, there used to be an option to create a virtual PayPal card for one-off purchases, which worked for most users, but I think it got killed by PayPal. I think there should be other virtual card options, but of course, that may be not convenient for you.

Unfortunately, this is against the rules of the App Store, as well as technically impossible, since an App Store purchase cannot be tracked to a user’s email address or any other identifier.