The first thing you need to do is log into your account page here https://www.wikitude.com/my-account/.
If you have an active subscription, then follow the instructions from the FAQ "How to change my payment method".
If you do not have an active subscription:
- Select the Subscriptions link from the top menu.
- Click on the specific subscription id you wish to change the payment method for.
- Click the Resubscribe button displayed right below the subscription details. This action will redirect you back to the checkout page where you will basically place a new order and you can fill in any kind of new payment method you wish.