Atera is using Microsoft specifically created tool to manage volume activation of Office called Office Software Protection Platform script (ospp.vbs). 
You can review their documentation here. 

Based on the Office version, and if the machine is 32/64 bit, this is how Atera fetches the Office version:
Office 2016/2019 (32-bit) on a 32-bit version of Windows
cscript "C:\Program Files\Microsoft Office\Office16\OSPP.VBS" /dstatus
Office 2016/2019 (32-bit) on a 64-bit version of Windows
cscript "C:\Program Files (x86)\Microsoft Office\Office16\OSPP.VBS" /dstatus
Office 2016/2019 (64-bit) on a 64-bit version of Windows
cscript "C:\Program Files\Microsoft Office\Office16\OSPP.VBS" /dstatus
Office 2013 (32-bit) on a 32-bit version of Windows
cscript "C:\Program Files\Microsoft Office\Office15\OSPP.VBS" /dstatus
Office 2013 (32-bit) on a 64-bit version of Windows
cscript "C:\Program Files (x86)\Microsoft Office\Office15\OSPP.VBS" /dstatus
Office 2013 (64-bit) on a 64-bit version of Windows
cscript "C:\Program Files\Microsoft Office\Office15\OSPP.VBS" /dstatus
Office 2010 (32-bit) on a 32-bit version of Windows
cscript "C:\Program Files\Microsoft Office\Office14\OSPP.VBS" /dstatus
Office 2010 (32-bit) on a 64-bit version of Windows
cscript "C:\Program Files (x86)\Microsoft Office\Office14\OSPP.VBS" /dstatus
Office 2010 (64-bit) on a 64-bit version of Windows
cscript "C:\Program Files\Microsoft Office\Office14\OSPP.VBS" /dstatus

In case, the OSPP.VBS file is missing, or no subscription can be found in this file, we will query the vNextDiag.ps1 file. 
Office version 2016 and up (64-bit) on a 64-bit version of Windows
powershell.exe -file "C:\Program Files\Microsoft Office\Office16\vNextDiag.ps1"
Office version 2016 and up (32-bit) on a 32-bit version of Windows
powershell.exe -file "C:\Program Files(x86)\Microsoft Office\Office16\vNextDiag.ps1"
Office version 2016 and up (32-bit) on a 32-bit version of Windows
powershell.exe -file "C:\Program Files\Microsoft Office\Office16\vNextDiag.ps1"

Important note: 

Before you run the ospp.vbs, ensure that:

• If you want to run the script on a remote computer, the Windows firewall allows Windows Management Instrumentation (WMI) traffic on the remote computer.
• The user account you will use is a member of the Administrators group on the computer on which you run the script.
• You run ospp.vbs script from an elevated command prompt.

Atera queries the devices for Office license each day (once every 24 hours) using the above scripts.

If the license status is LICENSED, Atera will report in the console under Software device information, and in the Auditor and Microsoft Licensing Reports, the product displayed under LICENSE NAME.

Software information under the device page: 

Auditor report:

Microsoft Licensing report:

Any other license status, such as NOTIFICATIONS or UNLICENSED means that the Office product was not activated as per MS documentation and Atera will not display Office as being licensed in the reports nor show it as being installed, even if locally on the device Office is working properly.

In these cases, you should check the error code to help you troubleshoot the activation issue.

If you see a dialog box that contains an activation notification, an error code is usually displayed at the lower corner. You can then run ospp.vbs /ddescr together with the error code to see the text of the error message. The text will help you better understand the issue and what to do to fix it.

Another way to obtain an error code is to run ospp.vbs /act on the client computer to manually activate Office. If activation fails, an error code will be shown.

You can check this Microsoft troubleshooting guide for more options. 

Notes:

• If ospp.vbs and vNextDiag.ps1 files are missing or if they were removed, we're fetching the Office version from the following registry keys:
  
  32-bit OS
  Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\X.0\Registration\{RegistrationId}\ConvertToEdition 
  or 
  Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\X.0\Registration\{RegistrationId}\ProductName
  
  64-bit OS
  Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Office\X.0\Registration\{RegistrationId}\ConvertToEdition
  or 
  Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Office\X.0\Registration\{RegistrationId}\ProductName
• You may get different results from the Software Inventory Report which is fetching the Office version from appwiz.cpl