In MoceanAPI Verify, we put our customer first and allow our customers to choose a desired charging model, one of them are "Charge Per Conversion"
The way it work is you only pay for successful conversion or code verification (i.e. your users have provided you with a valid code)
You do not pay for any unsuccessful attempts, we will try to reach out to your customer via various communication channel, if in the end it was not converted, we will not charge you a cent.
For further assistance, do raise a support ticket with our Support Team at firstname.lastname@example.org.