We use the term “Postpaid” for any kind of billing that happens after the user already acquired the service.
The CPO usually requires a B2B contract relationship which is the foundation for (usually monthly) billings, so that the CPO does not have to fear for the money owed to them.
The opposite of postpaid is the billing-method pay-as-you-go, where the user pays directly before charging.
Since this can be somewhat cumbersome, or because an EMP wants to provide a given budget to their users, there is also the option of a (re)chargeable deposit (“prepaid topup”).
This post is also available in: Deutsch (German)