Key operating principles

Billing "in arrears" — the amount that appears on the customer's invoice is the last amount submitted within a given billing cycle. Subsequent charge submissions overwrite the previous ones rather than summing up. The charge is submitted via the application/license/setPrice gateway.
Multiple charge submissions — a charge can be sent any number of times during a cycle, even daily. It is recommended to update the amount on an ongoing basis, in line with actual usage. It is also possible to submit the full charge for, e.g., a plan on the first day of the billing cycle.
No charge submitted = no billing — if the developer does not submit any charge in a given cycle, there is no basis for billing the merchant's invoice.
Commission — the amount submitted as the last one in the cycle is credited to the developer's balance after deducting the commission.
Customer limit — the developer cannot charge the customer an amount higher than the limit declared by the customer at the time of subscription purchase.
Billing cycle information — available via the next_invoice_day field (see API endpoints).