Freemium

The Freemium plugin attempts to encapsulate the Right Way to offer service subscriptions. It is built to handle multiple subscription plans (free, premium, premium plus, etc.), let you control your own invoices, and to interact with any merchant gateway that supports either automated recurring billing or credit card storage.

Freemium is a different beast from ActiveMerchant. Where the latter is optimized for one-off billing of credit cards (as in a retail environment), Freemium is optimized for storage and recurring billing of credit cards. This makes it a much cleaner and more complete solution for handling subscriptions. At the time of this writing, however, Freemium actually depends on ActiveMerchant because of its excellent CreditCard model, which I plan to steal.

This plugin was born out of my attempts to figure out the correct way to handle subscriptions. I decided that the safest/cleanest way was to simply keep track of how far out the subscription had been paid, and when that date came near, bill the subscription again to extend the paid_through date. The approach has turned out well, I think, though I strongly encourage anyone and everyone to review the processes in this plugin to make sure the assumptions it makes are appropriate.

Please see http://freemium.googlecode.com/svn/trunk/README for more information, including instructions for installation.