This looks common issues nowdays where we shared office applications accross multiple users from same server.
Make sure you’re using Volume Licensing for Office, not a retail key, which is better for shared environments.
Try to Use tools like the Volume Activation Management Tool (VAMT) or set up a Key Management Service (KMS) to handle activations.
you can also use below powershell script and put under task scheduler and make it weekly which will check office activation and reactivate again.
Define the product key
$productKey = "YOUR-PRODUCT-KEY-HERE"
Define the Office version path
$officePath = "C:\Program Files\Microsoft Office\Office16"
Change directory to the Office installation path
Set-Location -Path $officePath
Uninstall any previous product keys
cscript ospp.vbs /unpkey:XXXXX
cscript ospp.vbs /unpkey:XXXXX
cscript ospp.vbs /unpkey:XXXXX
Install the new product key
cscript ospp.vbs /inpkey:$productKey
Activate the product key
cscript ospp.vbs /act
Check the license status
cscript ospp.vbs /dstatus