It's freemium rather than a trial, so you can use it for free for as long as you want. (Assuming I'm understanding your request there.)
It does export a Muse bundle which is a ZIP archive containing a JSON with the position of the cards and, more usefully, flat files for all the media. PNG, TXT, PDF, SVG for the ink, etc. I regularly drop backups of this into Dropbox or iCloud.
Version control would be tricky because one of the big features is realtime streaming sync. Could be an interesting research problem to find a way to combine Figma-style realtime documents with something that can be checked into Git.
