I believe there is a "Crystal" softsynth plugin, perhaps that's it? You could look in your DAW's Plug-in Manager and see what's listed there. But removing our "Crystals.component" should be enough to stop the expired demo message.
Additional questions – 1) would there be any reason why I would need both AU and VST3 versions of my Eventide plugins (or any plugins for that matter)? (2) Am I going to notice a big difference in performance when I upgrade my Mac Mini from 8GB to 32GB RAM?
1) What plug-in format you use is up to you and what youi host supports. If your host supports both, then no reason to have both installed.
2) Yes, I expect there will be a noticeable difference in performance with that RAM upgrade.