We are transitioning all canvas game developers away from Facebook Credits to local currency payments by September 12, 2013, 90 days after breaking change announcement. The new payments system simplifies the purchase experience for users, improves the performance of the payment flow, and makes it easier for developers to price virtual goods for a global audience. For more information, please see our local currency payments overview.
Games on Facebook are built on a freemium model, which allows people to play for free and developers to sell in-game virtual goods for profit. Start building your business on Facebook with a fast and flexible payments solution.

Facebook Payments gives you a safe and easy way to enable people to pay for digital items in your game. Facebook Payments has:
A trusted brand. People on Facebook can feel comfortable storing their payment information with Facebook and buying with their Facebook credentials.
Global reach. Facebook Payments is available internationally and supports 80+ payment methods in 50+ countries.
Easy integration. Developers who use our Graph API and dialogs can easily integrate with our payments APIs to get started quickly.
See more at: Payments How-To and Payments Best Practices

Subscriptions: Expand beyond one-time payments with a new, recurring revenue stream from subscriptions. Entice new subscribers with a free trial and offer the renewal cycle that works for your game, whether that's weekly, monthly, or another time period. Game developers offering subscriptions have grown incremental revenue and increased engagement in their games.
See more at: Subscriptions Best Practices and Subscriptions How To
Payer conversion tools: Grow your paying users by taking advantage of features to help you convert players into payers, such as the Pay by Mobile feature to help you optimize your pricing and payment experience for people who want to charge purchases to their mobile phone bill.
See more at: Pay by Mobile How To
NOTE: Facebook Payments is the exclusive payments provider for Games on Facebook. Read more about the policy in our Payment Terms.