I’m transitioning my Mac app from paid upfront to freemium with an in-app purchase. The app in question has been available on the Mac App Store for quite some time, and it gained business customers who purchased it via the Volume Purchase Program. The grandfathering path for regular customers is straightforward. I can read out the original app version from the receipt and base the activation state on it, i.e. keep the app unlocked up to a particular original version and require an in-app purchase otherwise. However, since the VPP works differently and there’s no such information in the receipt, I was wondering what the recommended approach for grandfathering these customers is.