Until now, the label had been solely used in the 'Designed for Families' section but it will roll out to all in January.
The new label will show up right below the "install" button for the apps, making it nearly impossible to miss.
For devs, you will need to log into your Play Developer Console and check off whether the apps contain ads before January 11th to stay in compliance.
Source:
Android Authority
Written by: Andre Yoskowitz @ 19 Nov 2015 16:28