How do I get customer information back when using a PayPal subscription button

Question

I'm having a difficult time understanding the flow of the Subscription button for PayPal subscriptions. This is my goal:

1) User logs into my site and clicks the "Subscribe" button 2) PayPal handles the subscribing process 3) PayPal sends me a notification via an exposed IPN endpoint letting me know the customer is processed successfully.

What I'm having trouble with is understanding how I track the customer's unique id throughout this process. What I'd expect is to send the customer id along to PayPal and then PayPal sends that customer id back in the IPN call to let me know that customer 12345 has successfully been processed.

Is that what happens? How do I track the customer id throughout the subscription process?

Thanks

Answer 1

Use the 'custom' variable. Doc: https://developer.paypal.com/webapps/developer/docs/classic/paypal-payments-standard/integration-guide/Appx_websitestandard_htmlvariables/#id08A6HI00JQU