Background
I have a small app (here) for showing a list of apps.
Recently, I was informed that there is an app (here) that shows a list of purchased apps, including their prices.
I've tested it, and it indeed shows all of the purchased apps, just like on the Google Play website (here)
The problem and what I've found
I didn't even know it's possible to get such a list, so after I've searched the Internet, and here, I still don't get how this was done.
All I know is that this app uses some authentication from the user, to get the list of apps from his Google account.
And, all I've found is that there are some non-official libraries (most are very very old) to get information of apps from the Play Store, but nothing seems official.
The questions
What is the API that can be used to get information of purchased apps?
Can it do more ? Maybe perform search? Maybe show free apps that were installed? Maybe the time they were installed and uninstalled? And the categories of those apps?
Are there any special requirements for using this API ?