Hi,
You will get a MAK key. This key is used to update the license and continue to get security patches.
Each transaction for Windows 7 ESU licenses will generate a unique MAK key. If a customer purchases Windows 7 ESUs at multiple points in time, CSP partners will be able to see the full list of transactions in the Partner Center for that customer. The customer will also see the MAK keys and associated licenses in their Microsoft 365 Admin Center.
For your reference:
https://techcommunity.microsoft.com/t5/windows-it-pro-blog/purchasing-windows-7-esus-as-a-cloud-solution-provider/ba-p/1034637
Before you try to install and activate the Windows 7 ESU key, you should first ensure that all of the prerequisites are installed as outlined in Obtaining Extended Security Updates for eligible Windows devices. The ESU key for Windows 7 will not install properly if the prerequisites are missing.
https://techcommunity.microsoft.com/t5/windows-it-pro-blog/obtaining-extended-security-updates-for-eligible-windows-devices/ba-p/1167091
Hope above information can help you.
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