Many times you need apk of application installed on your device.
If you don't like ADs you can buy ADFREE
There may be many reasons for it
When you want to format/reset your device you may not want to re download all the apps instead may want to install from your computer.
This app will give you apk of installed applications or games, so you can take a backup of them.
So now you can share not only the link of your favorite app but also you can share apk of that app.