Recurring Billing with Dynamic Amounts month to month [duplicate]

Question

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Variable amount recurring billing [closed] (8 answers)

Closed 8 years ago.

Is there a billing system that exists where I can have recurring billing every month, and change the amount the client is charged each month using code? For example, one month a user uses our service for one week and is charged $10, but the next week they use the service for 3 weeks and are charged $30, then the following month they use it for weeks and are charged $20. Every system I've looked at you must manually change this value, and I was wondering if there was a system that allowed you to automate this process. Any help would be greatly appreciated, thanks!

Answer 1

I've done this using the PayPal Website Payments Pro API. First you create an initial transaction and retain the ID. Then have a cron run whenever you want to process recurring transactions and process what they call a reference transaction. You pass it the last transaction ID and give it a new dollar value. It'll process another transaction with the same information.

Limitations on PayPal's reference transactions are they can't be older than 12 months from the last transaction and I believe the dollar cap is $10,000.