Well I just went to their web site and there is no paid version that I can see but there is the one I now use Mr Tramp2  
https://www.genuinesoundware.com/?a=showproduct&b=40
 
And my routine is EDIT/ Select none  - File/Save - File/Export/ then close. many times as we all know it will still ask you to save after an export. That was when mine crashes. And yes the project might have been open for a few hours prior to this which might be the clue. I'll now pay attention. 
I only had 2 crashes that happened while editing midi. I was thinking it was Melodyn as I have been converting Audio bass tracks to MIDI on all my backing tracks when this went down. 
 
Here's a ponder, I would think melodyn will stay active after you convert audio to midi right? But would it be removed from the project if you delete the audio track you used? Including deleting it from the audio folder which is what I'm doing. 
Sorry for going OT. But it is another part of preventing crashes,, cleaning up projects. Mine will be used for live performance so a crash is not on my wish list! My goal is 100% Midi projects and use the Playlist live. I bought Home Studio as to be that much more stable and crash proof. And will use W7 :)