Do you know of an API which provides the data you want as having done some initial research I am not sure there is an API for this.
There is an Android published API:
But as the docs say it's very limited:
'Currently, the API allows you to check the status of or cancel a user's subscription purchase.'
And there are some unofficial ones I spotted from this post:
But these seem to be more for leaderboard style results across the entire market whereas I am guessing you are looking for more detailed stats on your own apps?