How to find a license key for Office 2021 installed back in 2022

binesu 0 Reputation points
2025-12-16T14:16:48.5966667+00:00

I installed Microsoft Office 2021 Home and Business for MAC back in December 2022. I purchased it online and arrived with the box containing the license key details. I successfully installed it without a problem. However, I recently updated my MacOS to Tahoe and recently unable to use my Office 2021. There was an "Activate" icon to Microsoft 365 which I usually ignored and still able to use the MS apps. Now, even if I close the "Activate" icon, everything is greyed out and I can't input anything from Word, Excel, and Powerpoint. I am now forced to use Microsoft 365 free trial just to use MS apps. Here is what I have done so far:

  • I have tried to downgrade my Microsoft apps back to previous versions but there seems to be no reliable source in the internet and youtube how to do it specifically for MacOS Tahoe. Maybe anyone can help me?
  • Second, some of these downgrades will require inputting the license key or that 25-character password to which I no longer have the physical card containing the product key and I am unable to find in the Microsoft website that specific product transaction. I ordered it from a third party by the way.
  • Third, I am really frustrated about this situation that I wanted to buy those cheap knockoffs from online shops. Any recommendations or alternatives? Hopefully these options do not pose security concerns on my laptop.

Hoping the community can help me with this one. Thank you for your time!

Microsoft 365 and Office | Subscription, account, billing | Other | MacOS

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  1. Anonymous
    2025-12-16T15:00:03.6866667+00:00

    Hi Binesu,

    Thanks for reaching out. I understand how frustrating it can be to lose access to Office after a macOS update, especially when you’ve already invested in a perpetual license. I'm here to help!

    First, try recovering your license key. If you redeemed your product at office.com/setup, it should be linked to your Microsoft account under Services & Subscriptions. If your box came with a PIN instead of the full key, you can retrieve the key at microsoft.com/mac/getkey. If you can’t find it there, contacting Microsoft Support with proof of purchase is the safest option.

    Second, since macOS Tahoe is newer, Office 2021 might not fully support the latest build. Uninstall using Microsoft’s license removal tool, then install the last compatible Office 2021 build from Microsoft’s official update history to avoid stability issues.

    Third, after reinstalling, sign in with the Microsoft account tied to your license or enter the recovered key. If activation still fails, check macOS permissions under Privacy & Security and allow full disk access for Office apps. This often resolves activation glitches after major OS updates.

    Last, if compatibility remains an issue, consider upgrading to Office 2024 for better support on the newest macOS.

    I hope you find this information helpful. Please let me know if you have any further questions If the answer is helpful, please click "Accept Answer".

    Regards,

    Carlo

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