For a native Android experience, the Google Play Billing Library is the standard for handling transactions securely.

: Ensure that once a download is "bought," it is linked to the user's Google account so they can access it across tablets, watches, or TVs. Purchase approvals on Google Play - Android

: If the download is a digital asset within an app (like a game level), use the IAP flow to unlock content immediately.

: For larger downloads, consider allowing users to change their download location to an SD card to save internal storage space.

: Within the Google Play Store, the "Buy" button automatically transitions to an "Install" button once the payment is processed.