We are not interested in any personal user information. No user data is collected by this application. It does not use your network and the internet.
Grainstorm is a sampler and it requests the sensitive "Record Audio Permission" when the microphone button is pressed and this permission is not already granted by the user. Everything recorded over the microphone is exclusively used inside the app as basis for sound synthesis.
The Upgrade process with all transaction details is provided and handled by Google. The app does not have access to data you may have to provide when upgrading. Please see the Google Payments Privacy Notice for further information.