You enter a Microsoft 365 product key at microsoft365.com/setup or office.com/setup, signed in with your Microsoft account, and you only do it once per key. After that, as of October 2026, your Microsoft account takes the place of the key for installing, reinstalling and activating.
Here's the catch. If a key you bought separately from the software doesn't work, Microsoft says it's very possibly stolen or fraudulently obtained and has been blocked. Its advice is to contact the seller and ask for a refund. Keys printed on counterfeit labels or cards, or sold with promotional or manufacturer reinstallation media, are the ones to be wary of.
A Microsoft key always looks like this: XXXXX-XXXXX-XXXXX-XXXXX-XXXXX. A key card can carry barcodes and other strings of letters and numbers, but the key is the one in that five-by-five format, sometimes under a silver foil you scratch off.
Where your key goes, by how you bought it
| How you bought it | Where to enter or find the key, as of October 2026 |
|---|---|
| A new key card or a key from an online store | microsoft365.com/setup or office.com/setup |
| A one-time Office purchase from the Microsoft Store | microsoftstore.com, then your name, Order History and Install Office |
| Workplace Discount Program: Office Professional Plus, Visio Professional or Project Professional | Inside the app, after I don't want to sign in or create an account |
| Microsoft 365 Business Standard | signup.microsoft.com/get-started/setupkey |
| Volume licence Office Professional Plus at work | Your admin |
| A new PC with Office included | Nowhere: a digital key arrives when you activate Windows |
Redeeming a new key
- Go to microsoft365.com/setup or office.com/setup.
- Sign in with your Microsoft account, or create one. Remember which one, because it's how you'll reinstall later without the key.
- If you're renewing, use the account already tied to your subscription.
- Enter the key without hyphens if you're asked. If there's no box, the key was entered for you.
- Follow the prompts to finish.
If you see This product key has already been used, the key is redeemed and you don't need it any more. Sign in at account.microsoft.com and install from there. On the Microsoft Store route, selecting Install Office only shows you the key, it doesn't install anything, and that key won't match the one on your Services & subscriptions page. Microsoft says that's normal: they're two different types of key in the same format.
To renew a subscription, you can buy a Microsoft 365 key card from a retailer and redeem it at the same setup page, or renew online with no key at all. If you damaged your key but still have a valid proof of purchase, Microsoft support may be able to replace it or offer other options.
A new PC with no key in the box
If you paid for Office or Microsoft 365 to come with a new Windows PC, you won't get a printed key. A digital product key is sent to the PC when you activate Windows, and you activate Office by signing in with your Microsoft account. After that, the product sits in your account and you can reinstall it without any key.
If instead you see a Let's get started screen offering to try, buy or activate, what's installed is a 1-month trial of Microsoft 365 Family. Your PC maker won't send you a key unless you paid for a product key card.
When Office asks for a key you don't have
For Microsoft 365 and individually bought apps like Word, Excel, Outlook, Visio and Project, use your Microsoft account, not a key, to install and activate. Make sure it's the account you bought with. The banners tell you what's wrong:
| What you see | What it means |
|---|---|
| SUBSCRIPTION EXPIRED in yellow or red | Renew your Microsoft 365 subscription to keep using Office |
| PRODUCT NOTICE on pre-installed Office | Start a Microsoft 365 Family trial, sign in with the right account, or buy Office |
| The Activation Wizard | Office needs your help to activate, so follow its prompts |
You can't see your full key inside Office, for security reasons. What you can see is the account it belongs to: open Word, go to File, then Account, and look for the email after Belongs to. You also can't view it online, except for older Workplace Discount Program purchases on your Order Details page. You can change the key on Office Home & Business, Home & Student, Professional and single apps, and switch licence if you move to Microsoft 365.
Activating volume and perpetual products
Since December 3, 2025, Microsoft has moved telephone activation for perpetual licences online to the Product Activation Portal at visualsupport.microsoft.com. Microsoft still recommends activating online first, and offline activation is still supported.
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- Open the portal and complete the CAPTCHA.
- Select Proceed to Sign In and use a personal, work, school, Entra ID or Azure Government account.
- Select Activate a Microsoft Product, then the product and version.
Signing in doesn't tie your account to the licence: it only secures access to the portal. It supports Retail, OEM, Volume License and Cloud Solution Provider licences, and admins can use Volume License Key Management to find keys or ask for a higher key limit.
My verdict on Microsoft 365 product keys
I'd treat the key as a one-time ticket. Redeem it straight away, write down which Microsoft account you used, and then forget the key exists. I'd steer clear of keys sold on their own, separate from the software, because a blocked key leaves you chasing a seller, not Microsoft. If you're deciding whether to buy at all, compare the Microsoft 365 prices with the free office suites first.
Frequently asked questions
Do I need a product key to reinstall Microsoft 365?
No. Sign in to the Services & subscriptions page with the Microsoft account you used to buy Office and install from there.
Why doesn't my product key match the one in my account?
That's normal. The key on your Services & subscriptions page is always different from the one on a key card or receipt.
Can I see my product key inside Office?
No. For security reasons, the full product key isn't displayed within Office.
What does This product key has already been used mean?
The key has already been redeemed and is no longer needed. Sign in at account.microsoft.com to install.
Why didn't my new laptop come with an Office key?
If you paid for Office on a new Windows PC, a digital key is sent when you activate Windows, so you won't receive a printed one.
