So my wife got this new Lenovo Yoga laptop, Windows 10 Home. It had the usual bloatware installed, including Office 365.

I installed Office 2013 and expected it to ask for a product key. Instead, a prompt for Office 365 came up, telling me that I had a 3 day free trial. I uninstalled (using Revo Uninstaller Pro) and then reinstalled Office, same result.

I found this "scrub" utility in a search.

It worked.