When you purchase Due, you unlock every feature today, including any new features that will be introduced in the next one year.
You'll always receive app updates from the App Store for free (Due debut in 2010 on iOS and has been updated since), which adds support for the latest iPhones, iPads and Apple Watch screen sizes, along with compatibility with the latest iOS and watchOS to ensure that the app continues to function well on them.
From time to time, Due will introduce new features, on top of these compatibility updates. After your one year of free feature upgrades is up, new features would require the Upgrade Pass to unlock.
The Upgrade Pass is an optional subscription that unlocks features permanently, even after the subscription lapses.
Any feature unlocked remains available to you forever.
The iOS Upgrade Pass is separate from the macOS Upgrade Pass. This allows us to offer the pass at a lower price to customers who use Due on just one platform.