legally you could not have the Microsoft app open on both computers AT THE SAME TIME. Enforcing that turned out to be highly problematic and I believe was a significant driving factor in Microsoft's decision to go to a software leasing model as opposed to sales.
Adobe (luckily) still allows
[1.1] office and home copies (2 devices, but not in use simultaneously), even with their leasing model, just as before the leasing model. How their software is used is easier to track now, and it is easier to do something about (serious) license violations.
