by Raam Dev » January 13th, 2012, 8:15 pm
The seller's PayPal account has a recurring subscriptions manager where active subscriptions can be canceled. The buyer (i.e., the subscriber) can also cancel the subscription from within their PayPal account.
As the seller, you can provide your customers with a cancellation button that will send them directly to the page on PayPal where they can cancel their subscription (see WP Admin -> s2Member -> PayPal Buttons -> PayPal Subscr Cancellation Buttons).
With s2Member Pro and Pro-Forms, you can provide your customers a cancellation form. When your customer clicks the cancel button, s2Member is silently notified by PayPal in the background and their s2Member account is delete/demoted).
According to PayPal's policy on recurring billing, you MUST provide each and every Customer with an easy to way to cancel future charges.
Finally, it is the responsibility (I believe) of the site owner to ensure that any current subscriptions are cancelled when taking down a site. As I said earlier, this can be done from the seller's PayPal account.