
You can follow along here.
https://support.microsoft.com/en-us/office/how-do-i-upgrade-office-ee68f6cf-422f-464a-82ec-385f65391350
as to licensing software assurance may be required, you can confirm by contacting a microsoft certified licensing specialist.
https://www.microsoft.com/en-us/licensing/licensing-programs/software-assurance-default
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