MS is really pushing the "cash grab" called subscription licensing (aka Office 365). Personally, I speculate that with the VNext release of Office (2019/2020?) they will do away with the old "per machine" licenses. (I hate the idea! as much as I hate losing
MSI installs in favor of all CTR installs)
For business users they are most insistent. If you buy 365 business licenses, then you can easily install and manage them through the "admin portal". That takes advantage of the "fast painless" background install of 365. I can give you links to more details
about 365 business admin if you wish.
If you wish to continue using the old style licenses all I can suggest is a really bad practice. Ask for their userids and passwords and tell them to change the passwords after you do the install. Yes, I know it is an atrocious idea from the security perspective.
I have a link, which I can't find at the moment, that says the install limit is 20-25 product keys on one email account.
You MUST record the product keys and computer ID (serial number) and email account you use to activate it for each machine. If you want to transfer the Office license / installation to another machine in the future (ie machine dies) you need the product
key. But after the activation is done, you have no way of figuring out the key used on that machine if the machine is dead. Which means you have also lost that license. If you go into the myaccount website with the generic email account, all of the product
keys associated with that ID are sorted alphabetically.
PS: I'll second MrCrusher's recommendation to avoid DELL OEM Office licenses (at least for the time being). As he pointed out, several people have had problems with the product keys being "stolen" somewhere along their supply chain.
PS: I call it a cash grab because a MS official has admitted that they can get up to 80% more revenue from some subscriptions (adobe has admitted they have up to doubled profits since going subscription).
2015 12 11- **Adobe: We locked our customers in the cloud and out poured money******
http://www.channelregister.co.uk/2015/12/11/adobe_q4_fy2015_results/
<snip>
... up 22 per cent year-on-year, driven by a 44 per cent hike in subscriptionsto $907.4m as products declined 13 per cent to $284.4m and services/ support dipped 1.7 per cent to $114.4m.
</snip>
2015 05 13- Office 365 subscriptions are great for Microsoft
http://new.office-watch.com/2015/office-365-subscriptions-are-great-for-microsoft/
<snip>
The latest financial disclosures from Microsoft show that the move to annual ‘subscriptions (rentals) mean a price increase to customers of up to 80%!
....
Finally, these admissions by Microsoft blow their cover on the ‘free’ offer of a Windows 10 upgrade. It’s being done to put customers on the path to an ongoing rental fee for Windows itself, either for additional features or for ongoing use.
</snip>