Get app download date to implement trial period?

[KlugerDavid]

Hi, I want to build an app with a trial period, and for that I need a way of getting the time when the app was downloaded. It's not very impressive if the user can just delete the app and reinstall it to get a new free trial period.

As I understand, at least for iOS it is possible to get this info from the app store using receipts, but I have not been able to figure out if it is possible to do it with this API, and if so, how? It is a use-case I think should be supported/documented.