You should be able to upgrade any amount of systems using the Easy Upgrade wizard.
Click Start > Settings > Update & security > Activation > Store > make your purchase.
How to Perform an Easy Upgrade in Windows 10
Ideally, you get an option to set up your account according to your personal use or to set it up for an organization.
Go to Settings > Accounts > On Your info page, click Access work or school > Connect.
On the Set up a work or school account dialog, under Alternate actions, choose Join this device to Azure Active Directory.
Since this is a technical forum and not a licensing one, if you need a definite answer you'd better contact your reseller or a trained Microsoft licensing specialist regarding your licensing questions.
Hope above information can help you.
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