UPDATE 2
as Kurru rightly points out in his answer, facebook credits can be redeemed to developers (just not to users). the Facebook Credits Terms says so, but in a quite convoluted way. better information can be found at Facebook Credits for Developers, incl.
- How can I get started with Facebook Credits?
- How much can I redeem a Facebook Credit for?
- What payment options do Facebook Credits support?
- What is the process to ensure timely payout for an app that integrates Facebook Credits, as well as additional apps by the same company?
- Which countries can Facebook Credits currently pay out?".
UPDATE 2 END
UPDATE
https://developers.facebook.com/attachment/FacebookCreditsIntegrationGuidev1.pdf , p. 14:
To build user trust, please follow both the Facebook Credits Terms and Platform Policies, including (but not limited to) the following:
Facebook Credits cannot be..
- cashed out into real-world currency
- used to enable person-to-person funds
- used to sell physical or real-world items
Details (Eligibility, (allowed) Transactions, Redemption, Actions We May Take, Transaction-Related Disputes, Other Terms) are in the Facebook Credits Terms.
UPDATE END
https://developers.facebook.com/docs/creditsapi/ :
The Facebook Credits API enables a user to use credits as a method for purchasing digital and virtual goods within a Facebook canvas application. Please note: the credits api is not yet available for use by external websites but only on canvas iframe applications.