I've been a user of SplashID password manager on my iPhone, iPad and Windows machine for a couple of years and found it pretty good. I paid $10 to use wifi sync which seemed reasonable value at the time.
Now, the developer has created an "upgraded" version which requires a $20 annual fee to use wifi sync. Of course they can offer this service and maybe some people will buy it, but I'm happy with my version thanks.
BUT - the version on my iDevices is linked to the App Store, and will automatically update if I enable this option or if I ever click the "Update All" button; there's no easy way to stop this, and thus at some point my paid for functionality will inevitably be deleted by the developer.
In my view this is ransomware (or possibly theft). The developer almost certainly doesn't intend it this way, but as a consumer I don't care what their theory is, I care what I can use and what it costs me. When I buy something I don't expect free upgrades, although they are often included, but I do expect it to not be remotely disabled and an additional fee demanded.
Of course there is a very simple solution - leave the application on the App Store and create a new one explicitely as "Version X". If the old one breaks with an iOS update then fair enough, I didn't buy perpetual support, but in the meantime don't steal my functionality.
Posts on the SplashData forum received suggestions to use their permanent upgrade offer - so basically ransomware in email form rather than as an in-app purchase.
I also raised this with Apple but haven't heard back yet.