https://arstechnica.com/gadgets/2020/02/apple-will-introduce-universal-app-purchases-for-ios-and-macos/

When Apple introduced Catalyst, its developers' toolkit for porting iOS and iPadOS apps to macOS, developers and users alike were quick to point out that they'd like to see universal iOS/macOS app purchases in the App Store. Now, Apple has told developers it plans to add that feature in March, along with a few changes to the App Store to accompany it.