How does my merchant website know autometically that my customers subsribe or unsubsribe?

[IanY]

There are many of tutorials on YouTube teaching you the method to setup subscriptions and recurring payments for a merchant website. However, they do not mention how a merchant website can get notified autometically when customers subsribe or unsubsribe.

For example, if my merchant website allows my customers to subscribe to monthly plan or yearly plan to enjoy premium services, how can my merchant website knows autometically when a customer subscribes to a plan so that it can enable premium services for that customer immediately, and how can my merchant website knows autometically when a customer unsubscribes to a plan so that it can disable premium services for that customer immediatly?

[MTS_Ciaran · Accepted solution]

how do..... 

So the best approach for this is to use IPN (Instant Payment Notification), this system issues a data message out to a URL on your site which includes the subscription data once a user subscribes or unsubscribes. 

You can get more details on IPN here:

https://developer.paypal.com/docs/classic/products/instant-payment-notification/

and the Subscription IPN variables are here:

https://developer.paypal.com/webapps/developer/docs/classic/ipn/integration-guide/IPNandPDTVariables...