According to Reuters, Google has warned several game and application developers that if they continue to use alternative payment methods such as PayPal, Boku and Zong, their apps will be removed from the Android Market, which has now rebranded as Google Play.
Google's payment service charges a higher cost per transaction that some of its rivals, but Google is thought to want Google Wallet to become the primary way in which users pay for all apps on Google Play.
In one email sent to a developer last August, Google warned the firm that they had 30 days to comply with the request to use Google Wallet or their apps would be "suspended" from the Android Market. Reuters obtained a copy of the email this week.
Papaya previously used PayPal and Zong, both owned by eBay, but it has now moved over to Google Wallet for all in-app billing.
Shen added: "If we had a choice, the freedom to choose which billing service, then that's even better. But if we have to follow the rules, we will.
"I want to maintain a very good relationship with Google. We are very collaborative. It's very important to the business."
It is thought that Google has moved to unify the billing across app store Google Play after seeing that Apple's iOS platform generates much higher conversion rates as developers have been forced to use Apple's payments system from day one.
The previous system of various different payment providers in the Android market is thought to have been confusing for some people and dissuaded them from making purchases.
"This is one of the things that has helped Apple succeed," said Charles Hudson, of Android games developer Bionic Panda Games
"Every single developer is using the Apple payment system. Google sees the benefits that provides for the Apple platform and wants to create a similar system."
Developers using Google Wallet typically have to pay Google a 30% cut of revenue from purchases, which is higher than third-party services, but the same as Apple charges for using the iTunes App Store.
Zipline Games chief executive Todd Hooper added: "On Android it used to be laissez faire - you could use any payment provider you liked.
"It's probably naive of developers to think they could keep choosing different payment providers. If purchasing on Android is all over the place, that is worrying."
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