We just reinstalled Windows, we launch Word, and the software asks for an Office product key that we never noted down. The situation is common, but the method to retrieve this key entirely depends on the type of license installed on the machine. Before rummaging through emails or running a PowerShell command, it’s important to first understand what we are looking for, because not all versions of Office operate in the same way.
Perpetual license, 365 subscription, or OEM: what changes for the key
The first thing to check is the type of Office license present on the workstation. An OEM license (pre-installed by the PC manufacturer), a Retail license (purchased in a box or online), and a Microsoft 365 subscription are managed very differently when it comes to activation.
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For OEM and Retail licenses, a 25-character key (format XXXXX-XXXXX-XXXXX-XXXXX-XXXXX) is associated with the installation. It can be found physically (sticker, card in the box, confirmation email) or through software tools.
For Microsoft 365, the situation is different. Most 365 subscriptions no longer use a product key: activation goes directly through the Microsoft account linked to the purchase. You log in to office.com with your credentials, and the installation starts without entering a key. Looking for a key for a 365 subscription purchased online often amounts to searching for something that doesn’t exist.
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To determine what type of license is on a PC, you can also use the Command Prompt. By opening a terminal with administrative rights and navigating to the Office installation folder, the command cscript ospp.vbs /dstatus displays the type of license and the last five characters of the active key. When you need to find your Office product key on a machine that is already configured, this is the most reliable starting point.
Recovering a lost Office key with the Command Prompt or third-party software
On a standard Office installation (2016, 2019, 2021, LTSC 2024), the key is stored in the Windows registry, but only partially. The Command Prompt reveals only the last five characters. This is enough to identify which key is active if you have multiple, but not to reinstall Office on another machine.
The Command Prompt method
Open the Command Prompt as an administrator, then enter the path to the Office folder (usually Program FilesMicrosoft OfficeOfficeXX). The command cscript ospp.vbs /dstatus returns the name of the license, its activation status, and the last characters of the key.
If the status shows “Licensed,” the activation is valid. If you see “Notification” or “Grace,” the key has not been accepted or the trial period is expiring.
Key recovery software
When you need the complete 25-character key, third-party utilities like EaseUS Key Finder or ProduKey can extract the key from the registry. These tools scan the registry entries related to Microsoft products and display the key in plain text.
- Download the utility from the official publisher’s site (not from a dubious download aggregator)
- Run the scan with administrative rights to access system keys
- Note the retrieved key and store it immediately in a password manager or an encrypted file
- Verify that the key corresponds to the installed version of Office (the software usually displays the associated product name)
Feedback varies on this point: some free utilities only display a generic key on recent OEM installations. If the retrieved key does not work during reinstallation, it’s often because the license is linked to the Microsoft account and not to the local registry.
Activating Office after a reinstallation or PC change
Once the key is found, activation occurs at the first launch of Word, Excel, or any Office application. The software provides a field to enter the 25-character key. After validation, Office contacts Microsoft servers to verify that the key is legitimate and that it is not being used on an excessive number of machines.
In case of a PC change, a Retail license can be transferred: you first deactivate Office on the old machine (via the command cscript ospp.vbs /unpkey followed by the last five characters), then you enter the key on the new one. An OEM license, however, remains tied to the original motherboard and cannot be transferred to another computer.
Phone activation when the server refuses the key
If online activation fails (error message related to an exceeded number of activations), Microsoft still offers phone activation. You select the option in the activation wizard, call the displayed number, and an automated system provides a confirmation code after verifying the installation ID.
Low-priced Office keys: what you really risk
You can find Office keys for a few euros on resale sites. The price is attractive, but the mechanism behind it poses a problem. Some resellers market keys from volume licenses intended for businesses, resold individually in violation of Microsoft’s terms of use.
Others sell not a key, but shared access to a Microsoft 365 account: you receive a username and password, not an individual license. Microsoft regularly disables these shared accounts without notice, which means losing access to all documents stored on the associated OneDrive.
- A legitimate Office 2021 or 2024 key costs significantly more than just a few euros, even in a digital version
- Volume license keys resold at retail may work for months before being blocked by Microsoft
- A Microsoft 365 Family subscription remains the most predictable format for multi-device use with continuous updates
For LTSC 2021 and LTSC 2024 editions, the perpetual license only provides access to security updates. No new features, no integrated OneDrive storage, no real-time co-authoring. The choice between a perpetual key and a 365 subscription primarily depends on what you expect from the software on a daily basis.
Keeping a copy of your key in an accessible place (password manager, digital vault) avoids having to restart the entire process during the next reinstallation. It’s a reflex that takes thirty seconds and saves an hour of searching on the day Windows crashes.