Apple has already enabled developers the option to merge all their applications when buying them in the App Store and Mac App Store through a single universal purchase for all their platforms. This means that with a single payment the user will be able to enjoy their application on their iPhone, iPad and Mac.
Apple announced last February its plans to merge all its platforms at the application store level. In this way, a user who wants an application available for both iOS and macOS You would only have to buy that app once and it would already be available for all your platforms (iOS, iPadOS, macOS, tvOS and watchOS). The apps will even share in-app purchases, so if you unlocked a feature for your iPad, you would have it unlocked for your Mac as well.
This new feature is, at least for now, something optional for developers, who may choose to use it or not. It is still possible that there are applications with independent purchases on each platform, as between the applications for iPhone and iPad, two platforms merged at the level of purchases from the beginning but that allow developers to choose to sell their apps separately for each one. of them if they wish.
Apple's intention is clear: give the macOS app store a boost. The Mac App Store is growing very slowly, with many developers opting to sell their applications from outside of the official Apple store. Remember that contrary to what happens in iOS, where only apps from the App Store are allowed to be installed, in macOS you can install applications from any source, even without signing, although Apple has disabled this option by default as a security measure for users. users. With this new possibility of including "packs" that include all platforms through a single payment, Apple wants many developers to put their apps in the macOS store and users are encouraged to use it.