Office H&S 20212 This copy already installed on another computer

Sign in to Word with the Microsoft account originally associated with Office Home & Student 2021 instead of entering the product key again, because a redeemed key is normally reactivated through that account.

Reactivate the existing license

1. Open the Microsoft account Services & subscriptions page and sign in with the account used when Office was first purchased or activated: ^1^
2. Confirm that Office Home & Student 2021 appears there.
   • If it does not appear, try any other personal Microsoft account that might have been used during the original setup.
   • The Office 2013 installation on the other PC is a separate product and does not use this Office 2021 entitlement.
3. Open Word → File → Account.
4. Sign out of any account shown under User Information, close all Office applications, and reopen Word.
5. Select Sign in and use the account under which Office Home & Student 2021 appeared. Do not enter the product key again.

Office Home & Student is a one-time purchase licensed for one computer. The “another device” message can also appear when Office regards the same computer as different after a hardware change—not only when Office was deliberately installed elsewhere.^2^

If the license appears but activation still fails

Check for a second Office installation that could be conflicting with Office 2021:

1. Open Control Panel → Programs → Programs and Features.
2. Search the list for Office.
3. If more than one current Office installation is listed, uninstall only the version you do not use. Do not remove Office 2013 unless it is unexpectedly installed on this laptop.
4. Restart Windows, open Word, and sign in again.
5. If only one installation is present, select Office in Programs and Features → Change → Online Repair, then restart and sign in again.

Microsoft documents that multiple Office installations can cause activation conflicts and recommends Online Repair when activation still fails.^1^

If Office was supplied preinstalled with the laptop

Only use this branch if Office 2021 originally came preinstalled and was activated without associating a conventional product key with a Microsoft account:

1. Open Microsoft Store.
2. Select Library → Apps or All.
3. Turn off Show installed products only, if displayed.
4. Find the Office product and select its Cloud download button.
5. Complete the installation and reopen Word.

Some preinstalled Office 2021 licenses must be restored through the Microsoft Store rather than through ordinary product-key activation.^3^

If the account shows Office 2021 but Microsoft still reports another device

Office Home & Student 2021 does not provide the same remote-deactivation control as a Microsoft 365 subscription.^4^ Contact Microsoft Support while signed in with the account that owns the license:

1. Open the Microsoft Support contact page: https://support.microsoft.com/en-US/home/contact?SourceApp=smc2&ContactUsExperienceEntryPointAssetId=www.microsoft.com
2. Enter agent support in the search box.
3. Select Contact Support.
4. Choose Microsoft 365 and Office → Technical Support, then request browser chat.
5. Ask the agent to verify or reset the activation for Office Home & Student 2021 on the original laptop.

Have the purchase details available, but do not post the full product key publicly.

References

1. Unlicensed Product and activation errors in Office
2. Activate Office after reinstalling or installing on a different device | Microsoft Support
3. Reinstall Office from the Microsoft Store app | Microsoft Support
4. [Office 2021, 2019, 2016, 2013](https://support.microsoft.com/microsoft-365-activation-licensing/office-install/deactivate-an-installation-of-office)