How to acticate office21 bought with HP PC 3 years back?

For Office Home & Business 2021 that came preinstalled on an HP PC, use this activation path:

1. Open Word or Excel.
   • If prompted, select Activate Office.
   • In many cases, Office activates after accepting the license terms.
2. Sign in with the correct account.
   • Use the Microsoft account that is associated with the Office purchase.
   • If the current Outlook/Microsoft account was linked only recently, it may be the wrong account.
   • Check whether the license appears under Subscriptions at https://account.microsoft.com/services.
   • If Office is not listed there, that account is not the one associated with the license.
3. Sign out of Office, restart the PC, and sign in again.
   • Open Word.
   • Sign out of Office from the app.
   • Restart the PC, then sign back in.
   • This is a known resolution in a similar Office Home & Business 2021 activation case.
4. Check for multiple Office installations.
   • More than one installed copy of Office can cause activation conflicts.
5. If the PC originally had preinstalled Office and activation still fails, start Office activation again from any Office app.
   • On a new or reset installation, the first launch should offer Try, Buy, or Activate Office.
6. If the message says the products in the account cannot be used to activate Office, update or reinstall Office 2021.
   • Update Office, then try activation again.
   • If needed, reinstall Office 2021 and then open Word or Excel to trigger activation.

For the 24 PCs, repeat the same checks on each device:

• verify the correct Microsoft account for that PC’s Office license
• confirm the license appears in Subscriptions
• remove duplicate Office installs if present
• reactivate from Word or Excel

If a given PC’s license does not appear in any Microsoft account, that device likely needs Microsoft support to recover the original entitlement tied to the preinstalled Office.

• Download and install or reinstall Office 2021, Office 2019, or Office 2016
• Unlicensed Product and activation errors in Office
• Can’t find Outlook, Access, or Publisher apps on a new PC that included Office
• Office error "The products we found in your account can't be used to activate"
• Office Home & Business 2021 activation failed - Microsoft Q&A