The team here at Chargify has been hard at work on a bunch of new features. We just flipped the switch on two of these: Prorated Upgrades/Downgrades and Metered Components.
Metered Components
Metered Components give Sellers the ability to charge for a product on a per-usage basis. For example, a cell phone provider could charge $1 for each text message that was sent, or a Web Hosting company could charge for storage by the number of gigabytes used. Creating metered components is quick and easy. Simply give the component a name, specify the unit used to measure it, and give it a per unit price. Usage of metered components is tallied throughout the billing cycle and the charge is seamlessly integrated as a line item on the Customer’s next invoice.

For more information on how to create Metered Components, and how to record usage via the API, see:

