You need to correctly understand and take into account in your work which methods and in what situations are considered paid if your service payment rate is based on calls (requests to OT API).
Firsly, only some of the methods are paid, mainly related to information from providers: catalog, products, product search, sellers, and so on. In this documentation, paid methods are marked with .
Any successful (in terms of OT API) calls to paid methods are taken into account. Those calls are considered successful if result contains an error code ErrorCode=Ok or ErrorCode=BatchError. If client, for some reason, did not wait for a response, but OT API still completed execution without errors and returned a result, this call is also considered successful.
As a separate addition, why BatchError error code is considered a successful call: such an error code can occur only in Batch methods, in case of errors in obtaining additional blocks of information (such as a block with a list of goods from the same seller in BatchGetItemFullInfo method). In this case, main information of the method (in the example, information about the product) is returned as usual, other additional blocks can also be successfully returned.
Some requests have a dynamic cost where multiple calls are charged at once instead of just one. In this documentation, paid methods are marked with .
Bulk methods of item getting typically have a dynamic cost based on the number of successfully received items.
Single methods of item getting, if ForceUpdate is set in itemParameters parameter, have a dynamic cost depending on provider, since each provider has its own difficulty of immediate item update.