it ask me to activate using internet it wrote to me that the license key has been used several times and i couldn't use it.
Could you please share us with a screenshot of this error message? Does an activation wizard appear, prompting you to activate by phone?
I suggest you sign your Microsoft Account into Subscriptions page, check whether the key was redeemed.
- If your key has been redeemed, it was bound with your account, there should be an Office 2021 shown under "Products you've purchased".
- Then please make sure there are no other devices with this Office installed.
If you've tried all your Microsoft accounts, there is no Office 2021 shown under "Products you've purchased", and no record of this purchase in Order History. It's recommended to contact the seller to confirm whether the key is valid.
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