How to activate Office 2021 step by step

Office 2021 Professional Plus is a perpetual package — you pay once and it stays yours, with no monthly subscription. Activation is simple, as long as you follow the steps in order. The most common problem comes from an old version of Office left on the computer.

Step 1: remove the old versions of Office

If you have an older Office or a trial version of Microsoft 365 installed, uninstall them: Settings → Apps → Installed apps, find Microsoft Office / Microsoft 365 and choose Uninstall. Restart the computer.

If the uninstall fails, Microsoft offers an official tool for completely removing Office (SaRA / Office Uninstall Support Tool).

Step 2: download the official installer

Download Office 2021 Professional Plus only from Microsoft’s official server. We send you the direct link in the email with your key, so you do not have to search for it. The file has the extension .img and is about 4 GB.

Step 3: install

1. Double-click the downloaded .img file — Windows opens it as a virtual drive.
2. Inside, find setup.exe and run it.
3. If Windows asks for permission, confirm.
4. The installation runs by itself and takes 10–20 minutes depending on the computer. Nothing is required from you.

Step 4: enter the key

1. Open Word or Excel.
2. A window appears asking for a product key. Copy the 25-character code from the email and paste it in.
3. Press Activate Office.
4. Accept the licence agreement — done.

If the activation window does not appear, go to File → Account → Activate Product and enter the key there.

If online activation does not work

Sometimes online activation returns an error — for example when the key has already been activated once on other hardware. In that case telephone activation is used:

1. In the activation window choose ‘I want to activate the software by telephone’.
2. You will see an Installation ID — a long number split into groups.
3. Take a photo of the screen and send it to us at info@litsenzi.bg together with your order number.
4. We send you back the confirmation code, which you enter in fields A to H.

We answer every day from 09:00 to 20:00, usually within 15 minutes.

Frequently asked questions

How many computers does one key cover?

One. Each licence is for a single device.

Can I reinstall Office on the same computer?

Yes, as many times as needed.

Do I need a Microsoft account?

For the Windows versions — no. For the Mac versions the licence is recorded in your Microsoft account; we recommend doing this within 5 days of purchase.

Office 2021 or Microsoft 365?

There is a comparison in this article — in short: 365 is a subscription with cloud storage and continuous new features, 2021 is a one-off payment that stays yours.

Where to buy a licence

Office 2021 Pro Plus includes Word, Excel, PowerPoint, Outlook, OneNote, Publisher and Access. The more economical options are Office 2019 and Office 2016. If you also need an operating system, the combined packages work out cheaper than two separate orders.