Zong, which bills itself as the “most frictionless” payment service for publishers of online games and other digital content, is launching a subscription-based mobile payment service.

Zong says it is now the first mobile payments platform to offer a subscription service, which allows Zong customers to extend a recurring bill-to-mobile option of up to $9.99 a month to their membership base.

The subscription service marks an extension of the company’s existing pay-as-you-go feature, which is on some of the largest social networking applications, virtual worlds and online games. The company says it reaches more than 1 billion mobile users worldwide.

Beginning today, the subscription service is available to all Zong customers looking to subscribe U.S.-based mobile users.  In the coming months, Zong says it will expand its subscription service to customers in Europe, Canada and Australia. Consumers can cancel a subscription via SMS, a phone call or the merchant’s Web site.

Zong is one of the fast growing alternative payment methods. Rival BOKU emerged in June with the combination of Mobillcash and Paymo. Earlier this month, BOKU announced additional merchants and publishers that use its solution to sell digital goods and services, and consumers use their mobile phone to pay.