Product Key Issues

How to Reinstall Office 2016 Professional Plus When Product Key is Already Used

Maira Mehtab Sep 22, 2026 869 views

Question details

The user needs to reinstall Office 2016 Professional Plus but receives an error stating the product key is already in use when attempting to activate the software.

Product: Microsoft Office 2016 Professional Plus
Device & OS: not provided
Scenario: Reinstalling and activating Office 2016 after a previous installation or hardware change.
Observed behavior: Office prompts for a product key upon reinstallation, but rejects the entered key by reporting it has already been used.

Before you start

Ensure you know whether your Office 2016 license was purchased directly through a personal Microsoft account or through an employer's Home Use Program, as this dictates the reinstallation method.

Solution 1Recommended

Reinstall via Microsoft Account Services

Use this method if your Office 2016 Professional Plus license is linked to your personal Microsoft account.

Retail and standard licenses are linked to your Microsoft account after the initial product key redemption. You do not need to enter the product key again to reinstall the software.

Sign In to Services

Open your web browser and navigate to account.microsoft.com/services.

Access the Linked Account

Locate Your Subscription

Scroll through the list of services and subscriptions to find your Office 2016 Professional Plus purchase.

Download and Install

Click the 'Install' button next to the product to download the installer and complete the setup without entering the product key.

Solution 2

Reinstall via Home Use Program (Workplace Discount)

Follow this method if your Office 2016 license was purchased through an employer's volume license or the Home Use Program.

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Frequently Asked Questions

Why does Office 2016 say my product key is already used?

A product key can typically only be redeemed once to link the license to a specific Microsoft account. Once redeemed, you must log in with that linked account to reinstall the software rather than re-entering the original 25-character key.

How do I find which Microsoft account is associated with my Office 2016?

You can check your email inboxes for past purchase confirmation emails from Microsoft. Alternatively, try logging into account.microsoft.com/services with your known personal or work email addresses to see if the Office 2016 license appears in the dashboard.

Can I transfer my Office 2016 Professional Plus license to a new computer?

Standard retail versions generally allow transferring to a new device by uninstalling from the old one first. However, Home Use Program or volume licenses may have specific device limitations set by your organization's IT policy.

What if I lost access to my work email for the Home Use Program?

If you no longer have access to the work email used for the purchase, you will likely need to contact Microsoft Support with your order confirmation details or original product key to request assistance with account recovery or license verification.

Installation & Activation