For every PayKickstart transaction there is a “purchase id” which are all prefixed with PK-P, followed by a random string. In the IPN POST it is referred to as the “invoice_id”.
There also is a “transaction_id” which are all prefixed with PK-T, followed by a random string. In the IPN POST it is referred to as the “transaction_id”.
Every purchase on the front-end will create a “purchase” and an associated “transaction”. In the IPN POST data, it is referred to the purchase id as the “invoice_id” and the transaction ID is referred to as the “transaction_id”.
For 1-off purchases you will receive a unique purchase id and a unique transaction id for each successful checkout.
For subscription purchases, you will get a unique purchase id and a unique transaction id the initial successful checkout, after which time each rebill transaction will be attached to the original purchase i.e. the purchase ID will NOT change, and each transaction associated to that “purchase” (subscription) will be linked to that purchase.
For example:
Purchase ID: https://app.paykickstart.com/admin/transactions?q=PK-PXXXXXXXX
And then by:
Transaction ID: https://app.paykickstart.com/admin/transactions?q=PK-TXXXXXXXX
In both cases the system will pull up the same transaction because the purchase in this case only has 1 transaction linked to it. If you searched using the purchase_id on a subscription in which rebills have already occurred, you’d see multiple transactions.