Here's a realistic scenario. I pay for CoolApp. It works fine even though CoolApp2 is live on the store. I get a new phone. I go to download CoolApp, but it's no longer available. If I want to use CoolApp, I must use CoolApp2.

I'm not expecting CoolApp to be forever supported. CoolApp works fine for my use case, so I planned on continually using CoolApp until it made sense for me to upgrade. But now that CoolApp2 is the only version available, I have to buy the newer version alongside my new device. If I turn on my old phone, I can still use CoolApp without skipping a beat. I think that's what the other commenter was getting at.

But that's not the case (at least not on iOS). Even if CoolApp has been removed from sale, you can download it on your new phone from your purchase history. The only exceptions to this are technical limitations on the old app that render it incompatible with the new phone such as 32 vs 64 bit, deprecated APIs, etc.

Even better if CoolApp 1.0 has been continuously updated for new OS’s and the newest version isn’t compatible with a device stuck on an older OS, you can download the “last compatible version”. I was able to download and use Netflix, Crackle, Plex, Hulu, Spotify and Google Drive on my 2010 first gen iPad that was officially abandoned in 2012.

I reset it and downloaded older versions of apps last year.

I have never owned an iPhone, thus I didn't know if that was possible. I suppose there's nothing to worry about.

Except that's not correct. If you've purchased CoolApp you can always re-install it via the previous purchases section of the App Store, even if the developer has removed it from sale. So you can continue using CoolApp as long as it continues to work on your iOS version and device.

That's the scenario I was thinking of. I think most of the debate on this thread is my use of 'non-scrupulous' to describe that scenario. Which is fair.

If CoolApp was a 32 bit app. You wouldn't be able to use it post iOS 10.

I personally think devs cross from scrupulous to non-scrupulous somewhere between 'this new version has no new features, but we changed the name of it so buy it again' and' 'we charge in-app for feature x, thanks for buying, but that payment is not enough to justify a free update'

Unfortunately, part of the blame is Apple's for not having a clean upgrade pricing solution. You can do it with app bundles but it's a hack.