
Hi @tienchai prasert
Office 2021 LTSC is volume licensed version, which uses KMS or MAK activation. Unlike the one-time purchase of the retail versions of Office, we do not need to transfer Office license.
- For KMS activation, make sure your computer is connected to the KMS host with more than 4 other KMS clients, and then apply for activation.
- For MAK activation, as long as you purchase enough activation licenses, you can reuse a MAK key for activation. If you need to request an increase to MAK activation limits, please refer to: https://learn.microsoft.com/en-us/microsoft-365/commerce/licenses/product-keys-for-vl?view=o365-worldwide#request-an-increase-to-mak-activation-limits
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