This is a subtle point about older devices that doesn't get enough attention imo.
In order to have an app I purchased with the features I purchased on an older device that I purchased, I must:
- Jailbreak the device
- Extract the iOS app and externally save it
- Turn off automatic updates for apps
- Be signed in to the Apple account that purchased that app
- Have that account be valid and not revoked
At some point, Apple may:
- Remove the app from the App store entirely
- Allow an update to the app that changes or removes the features that I specifically wanted
- Insist that the app does not support that older version of iOS (even if the version you purchased was fine, and only a later version removed support for older iOS versions)
In order to restore access to the app in that case I must:
- Jailbreak the device
- Sign in to that Apple account
- Copy the backed-up version of the app to the device
- Risk losing any data in that app, especially if it was updated and I'm now downgrading to a version that might not support the newer data format
The first let-down was Orphion: when I purchased the app it was amazing, but they used the finger touch API in a way that Apple did not agree with. They were forced to remove that API call in an update, and the app has not been the same since. Unfortunately I did not get a copy of the original version, and so I lost access to that specific experience that I paid for.
Everything else I buy for my home (except for things with obvious wear items that physically wear out), I expect to function forever exactly as the day I purchased it, or be repairable. I have hand tools that were made 100 years ago, inherited from my grandpa, which work exactly as they are supposed to. Yet, we're expected to accept that software "wears out" after a few years.