Old FAQ, license, and a relevant FAQ excerpt:
https://web.archive.org/web/20161108235524/https://www.virtu...
https://web.archive.org/web/20170126144347/https://www.virtu...
> Personal use is when you install the product on one or more PCs yourself and you make use of it (or even your friend, sister and grandmother). It doesn't matter whether you just use it for fun or run your multi-million euro business with it. Also, if you install it on your work PC at some large company, this is still personal use. However, if you are an administrator and want to deploy it to the 500 desktops in your company, this would no longer qualify as personal use.
Current license with the "noncommercial" requirement: https://www.virtualbox.org/wiki/VirtualBox_PUEL
> use solely by the person downloading the Product from Oracle on a single Host Computer, provided that no more than one client or remote computer is connected to that Host Computer and that client or remote computer is used solely to remotely view the Guest Computers.
This isn't a standard definition for "Personal Use" and I can now understand why people weren't happy.
[1] https://www.virtualbox.org/wiki/Licensing_FAQ