Does Microsoft make their unlicensed version available free of charge? (I didn’t know there was an unlicensed version!)
If so, there is absolutely no problem.
Most basic software functions can be obtained free of charge online, perfectly legal and ethical shareware, much of it open-source. Linux works great as an OS if you don’t mind hunting down “canonical this” and “canonical that” as add-ons for Ubuntu (which I find a royal pain myself, but maybe that’s just me). I run Linux on one of my machines. Open Office, while quirky here and there, works just as well as MS Word and Excel, at least for home purposes. I haven’t bought a software suite in years — it’s all shareware. (And do remember to make a small donation to the developers.)