There is no possibility to bundle the purchases from different Stores. 

Thus, the app should be purchased separately for each OS where it is going to be used. 

The iOS version of iStudiez Pro is available on the App Store

The app requires iOS 10 or later.

The macOS version is a stand-alone app and goes separately from the Mac App Store.

iStudiez Pro works on macOS 10.11 "El Capitan" and newer.

The Android version of the app is available on the Play Store.

The app runs on Android 4.1 and up.

iStudiez Pro for Windows 10 can be downloaded from the Windows Store.

If you are still on Windows 7 or 8, you may get the legacy app from our website.

Sometimes the Store may "forget" that you have already purchased the app and it shows you "Buy" button when you are trying to re-download the app.

If you use the same Store ID (email address) to download iStudiez Pro as the one that was used to buy the app, tap "Buy" button and you won't be charged again.

Otherwise, please contact Store Support Team.

NOTE: it works for re-download of iStudiez Pro on the platform you have already purchased the app before. 

For example, re-download of the iOS version of the app on your iPhone/iPad.
It doesn't work for other platforms (e.g. you've bought the app for Mac and trying to download it on iPhone).