At any time, it is possible to check the current state of a payment created earlier by repeatedly calling the POST method https://secure.octo.uz/prepare_payment specifying shop_transaction_id of the verified payment according to the described scheme.
Octo PS identifies a unique payment by the shop_transaction_id field - the differences of all other payment fields do not matter.
All payment parameters are fixed on the first call of prepare_payment, on subsequent calls, the status of the payment created on the first call will be returned.