Modify php-based small-size backend script

CB = [login to view URL] - digital products marketplace I am looking for changes on my php-based small-size backend scripts for ClickBank. Currently my backend supports CB one-time-paid product. I want to extend this by allowing subscription-based CB products. You need to add the support of x days trial period, rebill, cancel, refund (already implemented), fail1,fail2,fail3,fail4. Fails will need to PAUSE the account until a rebill or cancel comes. in case of cancel we will cancel either immediately within trial period or at the end of the paid month period after trial period. If user changes creditcard rebill date might shift... Current backend is using an API of a third party product mqllock dot com. this product is to manage license on my product. With basic and very detailed api we do activate, deactivate licenses there. Everything on mqllock is already implemented but you might need to implement the pause function if failed ipn notification arrives and recover after success.