I had this same problem with Office 2011 and migrating to a new computer. I talked with a few Microsoft techs extensively about this issue and pieced together what they said and did not say...and figured out what they have done to capture more control over activation and distribution:
Basically, you cannot just moved the files to another computer (or copy them) anymore, but now you will have to activate it by contacting them directly so they can put your Key code in their database, if you bought the program disk back in the day. They basically did not have record of your key code when you first activated it years back... i.e. errors at Microsoft back in the day. Hackers say, "Great", but Microsoft have figured out how to stop the hacking now after 30 years. (Good for them finally).
If you try to activate with your original Key code, you probably will not be able too do this until you contact Microsoft and activate directly over phone or their portal. If you use your original disk, it will probably not work to activate in most cases (though you can get the program files installed on your computer). You will have to use Microsoft's auto update to get the latest 'auto update file' on your system in order to activate, which collects info., put's some 'other files' on your computer etc. If not, when you launch one of the programs, the icon will just keep bouncing and do nothing. Rubber band fixes to the original program installation.
With the new management, Microsoft has put great efforts to take control of their software, including tracking everything (Now Microsoft is the 'hackers' into your computer), so Office 2011 is now one that they have concentrated on lately as well (understandable). The new updates are great for Office 2011, running faster etc, but once you update or restore from a backup or an old mac or install from the original disk again, you are locked into just one computer and that mac going forward. If you want to move it to another computer, you will have to activate it through Microsoft directly again with the hassles. Licensing has changed, so be aware. When I first bought the software, it was advertised and stated that I could put it on three macs...well, Microsoft told me that this is untrue...ONLY one system...now. Changed the rules...
If you have already installed it on a few of your macs and it is still running and activated, you are ok to update. But once you erase it or have to reinstall, that is it. ONLY one mac per key code.
All of that said, going forward...if you want Office 2011, you will have to pay for the key code if you want more than one copy (or have multiple macs). To get a copy now of Office 2011 is expensive, so if you don't have a key code now and need MSOffice, it is cheaper to get Office 2016 (not bad, but comes with the "new" Microsoft agendas).
