Actually with Office 365, you can install Office on an unlimited number of devices. You just can only use one per user account at the same time.
I've been on Office365 for about 6 years. i've given one of the subs to my dad. And with work offering the home discount, I get $30 a year off the sub price, so it's $69 per year for 6 subs. We use OneDrive a lot, so it's worth $69 a year for each account to have 1TB, getting office is just a nice bonus. And we also have Mac's and PC's, so Office 365 gives us copies of both.