Facebook is one of the most popular mobile apps on Apple's iPhone and Google's Android, though it makes no revenue from the programs.
California-based Facebook declined to comment on any plans for mobile Credits.
Developers of Facebook apps make money when users buy virtual items within their programs - say, a pony in Zynga's FarmVille.
When customers make those purchases using Facebook on a computer, the company gets its cut.
When it happens within the apps of Apple or Google, Facebook doesn't.
Facebook, which has more than 750 million users, makes most of its money from ads.
It's likely to generate more than US$2 billion ($2.2 billion) this year in earnings before interest, taxes, depreciation and amortisation, a source said.
The company is valued at US$72.9 billion on SharesPost, an exchange for shares of private businesses.
Facebook started testing Credits in 2009, in part to diversify its revenue sources.
The system lets users buy items in different games using a single virtual currency, with a commission going back to Facebook.
This year, the company made Credits mandatory for the sale of virtual goods in all applications on its site.
Virtual goods will be a US$20 billion market by 2014, estimates ThinkEquity.
Spending on mobile games alone will generate US$7.1 billion in sales that year.
- Bloomberg