Facebook announced two important changes to the social network's platform policies for app developers, in conjunction with the release of API version 2.1.

The changes involve the controversial in-app purchases and the incentivizing of users for accessing plugins or liking pages.

The first change tackles the issue of "freemium" games, which has been the subject of discussion due to their deceptive nature.

These games can be downloaded for free. However, what the user gets is only a basic version of the game. To move forward or to access certain features, users are required to pay certain charges. These extra charges may come for the unlocking of the next chapter of the game's story, for example, or for the purchase of items that can be used within the game.

In addition to the deceptive nature of "freemium" games, there have also been incidents when children made purchases worth thousands of dollars within these games, with the parents unaware that the "free" game that they downloaded for their child can lead to such charges on their credit cards.

The change in the platform policy now requires developers to state in the game's description if the app contains in-app purchases, whether mandatory or optional. 

"This is to give people a clear indication that your game may charge people during gameplay," wrote Facebook software engineer Harshdeep Singh on Facebook Developers page.

The second change will prevent apps and games from giving out incentives to users for accessing a plugin or liking a certain Facebook page. This rule includes offering in-game rewards for liking a page, or allowing a user to access a component of the game only when he or she has liked a specific page.

Not included in the policy is giving incentives to users for logging into an app, checking in at a location, or entering a promotion code.

"To ensure quality connections and help businesses reach the people who matter to them, we want people to like Pages because they want to connect and hear from the business, not because of artificial incentives," Singh wrote.

The change in this policy is part of Facebook's efforts to address the issue of "like farming," where a page is intentionally and artificially hit with likes, and once a certain number has been reached, the page is then changed to promote a different product or service.

Developers of affected apps have been given until November 5, a period of 90 days, to implement the necessary changes to their apps.