@atakan You shouldn't remove the main features that current users have already paid for if you're switching your app to a subscription-based business model. For instance, after you introduce a subscription model for new customers, allow customers who have already purchased a "full game unlock" to continue having access to the full game.
This, in my opinion, applies to Notability, and if enough users raise awareness of it, it might be possible for us premium users to continue using it without a subscription.
