About app developers that abandon support for the apps they sell

Nope. If attempting contact with the developer fails to elicit a response, there is nothing you can do. They’ve taken your money.

Any developer can abandon, withdraw, not update/maintain their App. These Apps eventually fall by the wayside - and if not updated for an extended period, as needed to maintain compatibility, they will eventually be pruned from the App Store by Apple.

If the App is a new purchase, and the App Store terms in your region permit it, then you may be able to request cancellation/refund of your App Store order.

Nope.

Technically, with iOS Apps, you only pay for the use of the app, just like most software, you never really own the software or app, you just pay for its use.

So, an iOS app developer/s can do what they want. If they simple aren't making enough money to constantly improve and update an app/s they can stop doing business any time they wish and abandon their app/s.

For some small app development companies, other factors could have played a part in an app being abandoned or removed from Apple's App Stores, even death of a key app developer's staff or founder OR if ONLY a single person app developer of app, maybe they just got tired with trying to keep up support of their app/s or maybe even died, in some extreme cases.

There are just too many reasons and circumstances why an app is no longer available from Apple's App Stores or from the general software marketplace and gets abandoned.

This happens to software businesses all the time. Sometimes in happens later than sooner, but this has always happened.

Apple's App Stores are just conduits for selling software. A software marketplace.

Apple is just making a large percentage off selling app developer software in their App Store marketplace.

Apple vets the software to make sure it conforms to all of Apple's App Store policies, rules and regulations and it conforms to Apple's App developments rules and specifications, but

Apple has NO controls whatsoever on what Apple app developers do or do not do with their software after all of this criteria has been met and done.

Sorry

Software licenses include the clause that the developer has the legal right to walk away from the product any time they wish, and there is nothing the end user can do about it. Even big developers like Microsoft do it. MS only supports their iOS apps for the current and previous versions of iOS and abandons support for older versions every time a new iOS comes out.

See -> Apple - Legal - Licensed Application End User License Agreement (clause e - software is provided “as is” and “as available”)

A lot of small developers simply find they cannot afford to keep supporting their apps as those apps ain’t paying the bills, as it turns out. Others only release an app to establish some credentials in software development so they can build a professional career from it. Many of the successful ones are bought by larger enterprises who are not interested in keeping the app alive, but want that code for their own internal product development and offerings (think Siri). So there are lots of reasons apps get dropped by the wayside.