Zuora claims its tool is the "missing link" that will make the Facebook economy a reality. The start-up says that, until now, the developers of the 52,000 Facebook applications currently in existence have only been able to make money through advertising.

Z-Commerce will now enable developers to charge for their applications using recurring pricing, usage-based fees, one-time charges or subscriptions.

Tien Tzuo, CEO, Zuora, says: "Everyone knows that, even though Facebook is hugely popular, it lacks a genuine revenue model for applications. Facebook's potential won't be realized until there is a viable commerce engine - this is what Z-Commerce for Facebook is all about."

Z-Commerce includes an online console for developers to register their applications with Zuora, set up price plans and view which Facebook users have subscribed to which apps.

Developers can also add pre-built widgets directly into their application, to handle subscription sign-ups, update billing and view subscriptions, invoices and payments. The system also lets developers limit access to applications to subscribers.

Zuora introduced its first product, Z-Billing, last May and says it wants to build the "PayPal for the subscription world". PayPal president Scott Thompson joined the board in September and the following month the firm announced a series B funding round of $15 million.