Yes! Now you can earn free credits that can be used to purchase apps from google play store. The process is pretty simple. Just download the app ‘Google Opinion Rewards‘ from Play store and follow the instructions given in the app. All you have to do is to complete some short surveys (typically takes 30 seconds to complete!) sent by Google to improve its services. So far, I have earned $10.06 (can only be used in Google Play store)!
The following video will show you how to actually get free credits using the app. Enjoy useful paid apps for free!