You can actually download paid apps on play store with the help of an app called APPVN
To Download Paid Apps for free using Appvn
1. After installing, open the AppVN. Then you will have to change the language to English by tapping on the MENU and Tap on Cai Dat (settings).
Then scroll down again to Cai dat ngon ngu (set language), tap and open it. Change your language to English.
2. To download paid apps for free, simply go to Google Play Store and locate the paid app you want to download, scroll down to SHARE, then tap on AppVN in the options