Hello there,
Was the payment made to office service?
What is the exact error that is preventing you from using the product?
If it is application based the community can help you but if this is related to payment you must contact the Microsoft billing and support to get this sorted as they might look into your account and the payment details.
Unlicensed Product and activation errors in Office https://support.microsoft.com/en-us/office/unlicensed-product-and-activation-errors-in-office-0d23d3c0-c19c-4b2f-9845-5344fedc4380
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