How to Activate Microsoft 365: Step-by-Step Guide
Bought Microsoft 365 and need to activate it? There are two ways: with a product key (if you bought a code) or by signing into your Microsoft account (if you subscribed online).
Both methods take about 2 minutes. Here's exactly what to do.
Which Activation Method Do You Need?
Use a Product Key if...
- You bought a boxed copy from a store
- You purchased a digital key from a retailer
- You received a 25-character code (XXXXX-XXXXX-XXXXX-XXXXX-XXXXX)
- Your employer gave you a license key
Use Microsoft Account if...
- You subscribed at microsoft.com
- You bought through Microsoft Store app
- Someone shared their Family subscription with you
- Your school/work provided access through your email
Activate with a Product Key
Got a 25-character code? Here's how to redeem it:
- 1
Go to office.com/setup
Or microsoft365.com/setup — both work.
- 2
Sign in to your Microsoft account
Create one if you don't have it. Use an email you'll remember.
- 3
Enter your 25-character product key
No dashes needed — it auto-formats. Key looks like: XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
- 4
Select your country and language
This affects which version you download.
- 5
Click 'Next' to redeem
The key is now linked to your Microsoft account permanently.
- 6
Download and install
Click 'Install Office' to download the apps. They'll be activated automatically.
Important: Each key works once. After redemption, it's tied to your account forever. Don't lose your account credentials.
Activate with Microsoft Account
If you subscribed online, activation is even simpler:
- 1
Download Office apps from office.com
Sign in with the account you used to subscribe.
- 2
Install and open any Office app
Word, Excel, or PowerPoint — any will work.
- 3
Sign in when prompted
Use the same Microsoft account as your subscription.
- 4
Done
Apps activate automatically. No key needed.
If apps say 'Unlicensed' after signing in, go to File > Account and click 'Sign out', then sign back in.
Check Your Activation Status
Not sure if it worked? Here's how to verify:
- 1
Open Word, Excel, or PowerPoint
Any Office app works.
- 2
Go to File > Account
On Mac: Click the app name in menu bar > About.
- 3
Look at 'Product Information'
Should show 'Microsoft 365' with 'Subscription Product'.
- 4
Check the user
Your email should appear under 'Belongs to'.
If activated, you'll see:
- • Product name: Microsoft 365 (Personal/Family/Business)
- • Subscription Product (not 'Product Activation Required')
- • Your email address shown
If NOT activated, you'll see:
- • 'Product Activation Required' banner
- • 'Unlicensed Product' warning
- • Limited functionality (can't edit, only view)
Fix Common Activation Errors
'This product key has already been used'
Cause: Someone already redeemed this key — possibly you on another account.
Fix: Check if you signed in with a different Microsoft account before. Try office.com/myaccount to see your subscriptions.
'We can't verify your product key'
Cause: Typo in the key, or the key is invalid/fake.
Fix: Double-check every character. If bought from a third party, contact them — you may have received a fraudulent key.
'Unlicensed Product' after signing in
Cause: Signed in with wrong account, or subscription expired.
Fix: Go to File > Account > Sign Out. Sign back in with the correct email. Check subscription status at account.microsoft.com/services.
'Your account doesn't have a license'
Cause: Subscription not linked to this email, or it expired.
Fix: Verify you're using the same account that has the subscription. Check at microsoft365.com/account for active subscriptions.
'Too many installations'
Cause: You've exceeded the device limit (5 PCs/Macs, 5 tablets, 5 phones).
Fix: Go to account.microsoft.com/devices, sign out from devices you no longer use, then retry.
Activation works but expires next day
Cause: Network or license sync issue.
Fix: Make sure you're connected to internet. Sign out and back in. If on corporate network, try from home.
Still Stuck?
- 1. Run Microsoft Support and Recovery Assistant: Download from aka.ms/SaRA — it fixes most issues automatically.
- 2. Contact Microsoft Support: Go to support.microsoft.com and start a chat. Have your product key or account email ready.
- 3. For business accounts: Contact your IT administrator — they manage your license.
Frequently Asked Questions
Can I activate on multiple computers?
Yes. Microsoft 365 allows 5 PCs/Macs, 5 tablets, and 5 phones. Install on all, sign in, and they all activate.
What if I forgot which account I used?
Try signing in with all your email addresses at office.com. Check each one's subscription status at account.microsoft.com/services.
Can I transfer my key to someone else?
No. Once redeemed, the key is permanently tied to your Microsoft account. You cannot transfer or resell it.
Do I need internet to stay activated?
You need internet to activate initially and for periodic license checks (roughly every 30 days). Offline use works between checks.
Will reinstalling Windows deactivate Office?
No. Your license is tied to your account, not your device. Reinstall Office, sign in, and it reactivates.
What if my subscription expires?
Apps switch to read-only mode. You can view files but not edit. Renew to restore full access — no data is lost.
Pro tip: Bookmark account.microsoft.com/services — this is where you can always check your subscription status, payment methods, and sharing settings.