Just to add on top of my last reply, FedEx or UPS, any account can be connected by the app and the charging takes place like this. You would have to set up a payment method that would directly be connected to your UPS or FedEx account. For example, when you create a set of FedEx developer credentials for connecting the API, you will need to add your card into it so that if and when you go live, you will be charged from it.