This is an overview of what occurs when someone purchases a subscription on your Web site. (You must have IPN all set up like the install.txt files says to.)

-User clicks the PayPal button on your site and is taken to Paypal.

-If they have an account they can log in, if they do not, they can skip this step and enter all of their billing info.

-If they do not have an account, Paypal asks them to choose a password. In this non-invasive manner, they create a Paypal account for them based on just their e-mail + password.

-PayPal generates a subscription and charges the first payment. Both parties get notification from Paypal that a subscription has started.

-If the user wants to cancel the subscription, he must log into his PayPal profile and cancel it from there. You can also cancel the subscription yourself from your own PayPal account.

-Payments are charged automatically every subscription period until the user cancels. When the user does cancel, both parties get notification, so you can delete the link if you must.

Thanks to phpLD user Tires for posting this.