...
A user may purchase a License for themselves by calling the create license endpoint. In order to create a license, some method of payment must be provided. At the moment only one method of payment is supported: "billing". With this payment method, no further payment details are necessary, but the user is charged through the service provider's billing system.
Purchase restrictions
Some users may have restrictions set on their account that prevent them from making purchases.
Billing
If the service provider supports billing as a payment method, then they are responsible for handling the billing of the customer separately. A list of all purchased licenses can be obtained through the management API. The order ID of a license uniquely identifies each purchase. This identifier should be used to make sure the user is not billed multiple times for the same purchase.