The Google Play Developer Program Policy (“Content Policy”) updated. Improvements include the addition of clarifying language for existing policies, support for new Google Play features and content, as well as the introduction of a new section addressing ad behavior in apps.
Visit and familiarize yourself with the above policies. If you find any existing applications in your catalog to be in non-compliance, Google ask you to remedy and republish the application within 30 calendar days of this notification. After this time period, applications discovered to be in violation may be subject to removal from Google Play. Any newly published applications must adhere to the latest version of the Content Policy for Google Play.
Source: Google Play for Developers - Google Play Developer Program Policy (“Content Policy”) Update.