With CIM, you set up a profile and billing profile for each person (using hosted CIM popups if you want easy PCI compliance), then use an automated script of your own to generate charges against those billing profiles. For instance, if you're charging people once a month, your script would run every morning, query your database for "give me all active subscriptions that are active and a month or more from last billing" and then generate a charge for each one, updating the status in your database depending on whether the charge succeeds or fails. The advantage of this method is you have total control over the charges, and can vary interval, charge amount every bill if you feel like it. You can do on-demand charging, even, as in charge whenever the customer balance goes over a certain amount. It's also slightly more reliable, since you don't have to worry about dealing with any occasional silent post failures.
