thrubluelenses
Mark,
I hope this is helpful and the fine folks at ProjectWizards can correct whatever I get wrong.
My understanding is you can use Express fully on any Mac that has a proper SetApp license. That will let you "see" a MP file, but just the features available in Express (as Vicky Noted. If you want to edit Express created docs on multiple computers, as you likely know, there are a few SetApp license options. If Express is all you are need, then you could pay $15/month (at least in the US) for the PowerUser plan. See attached.
On the other hand, if you own the full version of MP, depending on how/where you bought it, you could also, "...activate up to 5 personal devices. Merlin Project can however not be used for editing documents on multiple devices simultaneously." At least that is what my license offers. You can view MP files on any Mac without a license at all, you just can't edit them.
