I have a microsoft 365 family account. I just bought a new PC that came with a personal account.

Question

When I try to log in to microsoft 365, I get a message that I already have an account.

Answer 1

On the new PC, uninstall the preinstalled trial version and then install Microsoft 365 Family from your account at https://account.microsoft.com/services.

Answer 2

The message appears because the new PC is signed in with a different Microsoft account (the “personal” account that came with the PC), while the Microsoft 365 Family subscription is associated with another Microsoft account.

To use the existing Microsoft 365 Family subscription on the new PC:

1. Identify which Microsoft account has the Family subscription
   • Go to the Microsoft account, Services & subscriptions page.
   • Sign in with the account believed to own Microsoft 365 Family.
   • Confirm that Microsoft 365 Family appears under Services & subscriptions.
2. Sign out of the wrong account in Office on the new PC
   • Open any Office app (Word, Excel, etc.).
   • Go to Account (or File > Account).
   • Sign out of the current account shown there.
3. Sign in with the account that owns Microsoft 365 Family
   • In the same Account page in the Office app, choose Sign in.
   • Sign in with the Microsoft account that has the Microsoft 365 Family subscription (from step 1).
   • This associates the installed apps on the new PC with the correct license and activates them.
4. If someone shared Microsoft 365 Family with another account
   • If the Family subscription was shared to a different Microsoft account, use that shared account to sign in to Office on the new PC.

Key points from the behavior:

• A Microsoft 365 or Office license is always tied to a specific Microsoft account; that account must be used to install and activate the apps.
• Product keys are only used once to redeem the subscription; after that, installation and activation are done by signing in with the correct Microsoft account, not by re‑entering the key.

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References:

• Why do I need an account to sign in to Microsoft 365 or Office?
• About accounts in Office
• "This product key has already been used" error in Office
• Get help with product key errors on Office.com/setup