The honest answer is "it depends where the data actually lives"

Every app in this category will, eventually, either stop being maintained or stop being the tool you reach for. The question that matters is not whether that happens — it happens to well-liked software all the time — but whether your years of ratings, tags and arranged boards are stranded when it does.

Pixave is the case worth knowing, because it is checkable rather than hypothetical: its Mac App Store listing still shows version 2.3.13, updated 23 November 2020. Nobody has announced anything, which is exactly the point — a quiet app does not send a warning before the day you need to open it on a new Mac and discover the listing has not moved in years.

Two different places the answer can come from

The files on disk. If images were never copied into the app's own storage — indexed in place, the way Coii Ref and some others work — the pictures themselves were never at risk in the first place, whatever happens to the software. What can still be lost is everything the app added on top: ratings, tags, notes, and any board built inside it.

What the app exports. This is where the real difference shows up. An app that writes ratings and tags directly into the files as metadata, the way Adobe Bridge does with XMP, or beside them as a sidecar file where the format can't hold it, leaves that work readable by anything else that understands the same standard — including after the original app is gone. An app that keeps that layer only in its own database needs you to have exported it, on purpose, before the day you actually need it.

Where canvases specifically tend to get lost

Ratings and tags are usually the easier case — plenty of tools export them. A composed board is the harder one, because "export" rarely means the same thing for a canvas as it does for a flat list of metadata. Coii Ref's answer is to never put that question off until an export is needed: a board is a .coii-canvas file — plain JSON, in your own folder — from the moment it is saved, so there is nothing to migrate later because nothing was ever held anywhere else. refern takes a related but not identical position: its own FAQ states plainly that "your library is stored in normal folders on your disk" and nothing happens to your files if you stop paying, which answers the images half of this question convincingly. What it does not publish is the canvas format specifically, which is worth checking for yourself if a board you built is the part you'd mind losing most.

The question to ask before you build anything you'd miss

Not "is this company healthy" — that is not answerable from outside, and it is not really the question driving the anxiety anyway. The answerable version is: if I exported everything today, what would I actually get, and could I open it without this app installed? Local-first software is the term for the design that makes that answer "basically everything" by default, rather than a feature you have to remember to use. The comparison against Pixave walks through what a migration actually looks like once you decide to move, rather than leaving it as a hypothetical. Or try Coii Ref against your own library for thirty days and check the claim yourself with cat rather than take it on trust.