Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Eddie:
As Ron B has already pointed out, (in theory) you can use a single email account to install 20-25 Office 2016 licenses, ie
**Office 2016 / 2013/365 Installation and Activation Guide & FAQ**with Pictures -Specifically says you can activate 25 licenses on a single ID
Note: if you do that, you MUST keep your own record of the **full product key,**and computer ID used for each machine. You cannot depend on MS to provide that information for you later. You can NO LONGER "extract" the full product key from the computer.
Don't hold your breath waiting for MS to remove the requirement to associate the license with an email account. There are too many advantages for MS to maintain that relationship. The only way that will happen is if MANY really large customers move away from Office and tell MS that is the reason. But I don't expect it to happen because most large customers are "drinking the coolaid" and switching to 365 subscriptions. In many places this changes office from a "capital" expense that has to be depreciated over several years, to a "current expense" that can written off of their taxes in full each year ...
So, if your customers do decide to "vote with their feet (and wallet)" by moving away from Office, make sure to contact MS every time and tell them why this is happening.