According to media reports, Apple is planning to soon crack down on services that promote apps and games from other developers, following the removal of app discovery service AppGratis from the App Store. AppGratis was pulled from the iOS App Store earlier this week, as Apple told the company that its popular app and game discovery initiative had broken guidelines to do with promoting apps from other studios. Notably, AppGratis is far from the only company that does this, and plenty of other similar services are still alive and well on the App Store. However, All Things Digital reports that it has been informed by sources that the removal of AppGratis was just the beginning, and that Apple plans to enforce these guidelines even further, removing more discovery apps in the process. This isn't the first time that Apple has attempted to crack down on incentivized downloads. Back in 2011, the company began pulling down apps that incentivize users to install other apps in exchange for in-game currency. And at the end of 2012, the company looked to be causing problems for services like Tapjoy that incentivize app downloads to help developers acquire users.