Installing and activating Windows 11
You will land on this page in one of two situations: Windows 11 is already on the computer and you only need to enter the key, or you are starting from scratch. The first takes a minute. The second takes about half an hour, and for most of that time the computer works on its own. If you also bought Office, continue with the Office guide once Windows is done.
If Windows 11 is already installed
- Open Settings → System → Activation.
- Next to Change product key, click Change. If the computer runs Windows 11 Home and you bought Pro, first expand Upgrade your edition of Windows — the option is there.
The key is changed in Settings → System → Activation. - Enter the 25-character key from the email, click Next and then Activate.
You can type the key with or without the dashes.
If the key is for Pro and the computer runs Home, Windows upgrades to Pro without a reinstall. The computer restarts once, and your files and programs stay.
Check
On the same screen, Activation state should show Active. For a second check, press Windows + R, type slmgr /xpr and press Enter: the message should say the machine is permanently activated.
If you can't find the option to change the key, or Windows shows an error, see how to check your licence and what activation errors mean.
If you are installing Windows 11 from scratch
Before you start
- The computer must meet the requirements: TPM 2.0, Secure Boot and a reasonably recent processor. The check takes two minutes and is described in this article. If your computer doesn't qualify, Windows 10 Pro is the right choice.
- A USB stick of at least 8 GB. Its contents will be erased, so move your files off it first.
- A backup of your important files: a clean install erases everything on the drive.
- An internet connection and a Microsoft account — Windows 11 usually asks for both during the initial setup.
Step 1 — download Microsoft's tool
Open the official Microsoft page for Windows 11 and start the download in the section on creating installation media. This downloads Media Creation Tool.
Don't download Windows from other websites. The installation files are free and come straight from Microsoft — you only pay for the licence.
Step 2 — make a bootable USB stick
- Plug in the USB stick, run Media Creation Tool and accept the terms.
- Leave the language and edition as suggested, unless you need a different language.
- Choose USB flash drive, click Next and select the stick.
Choose the USB stick as the media. - Wait while the tool downloads Windows 11 (a few gigabytes) and prepares the stick. Depending on your connection, this takes from 15 minutes to about an hour.
If Media Creation Tool won't run, download the ISO file from the same page and make the stick with the free Rufus program. The result is the same.
Step 3 — boot the computer from the USB stick
- Leave the stick plugged in and restart the computer.
- Straight after it powers on, press the boot menu key several times. It is usually F12, F11, F9, F8 or Esc, depending on the make.
- Choose the USB stick from the list. The entry usually starts with UEFI: followed by the name of the stick.
The menu looks different on every make, but the USB stick is always in the list.
If the computer still loads the old Windows, go into the BIOS/UEFI settings (usually with F2 or Del) and put the USB stick first in the boot order.
Step 4 — install
- Choose your language and keyboard and click Next.
- Choose Install Windows 11 and tick the box to confirm that everything on the drive will be deleted.
This option performs a clean install. - Enter the product key, or choose I don't have a product key and enter it after the installation — the result is the same. If you choose the latter, Setup asks which edition to install: choose the one your key is for (Home or Pro).
You can also enter the key later. - Accept the licence terms, choose the drive and click Next, then Install. If the drive has old partitions, you can delete them so that only unallocated space remains.
Choose the drive Windows will be installed on.
The computer will restart several times — that is normal. At the end, Windows takes you through the initial setup: region, network and account.
If you want to keep your files and programs, don't boot from the USB stick. Open the stick from your running Windows and run setup.exe — this upgrades the system without deleting anything.
Step 5 — activate
If you entered the key during installation, Windows activates itself as soon as it connects to the internet. If you didn't, go back to the start of this page: Settings → System → Activation → Change product key.
The screenshots are simplified illustrations. Your windows may look slightly different depending on your version of Windows, but the labels and the order of the steps are the same.
If something goes wrong
- The key is not accepted — usually the edition doesn't match: a Home key can't activate Pro. (A Pro key on a Home computer is not an error — it upgrades the system to Pro.) The other causes are collected in our article on activation errors.
- Windows deactivates after a hardware change — that is normal, because activation is tied to the motherboard. The fix is in the guide to transferring a licence.
- Media Creation Tool closes without a message — use the ISO file and Rufus, as described in step 2.
- Nothing helps — email us at info@litsenzi.bg with your order number and a screenshot of the message. We help with activation free of charge, and if the key really doesn't work, you get a replacement or a refund.
Don't have a licence yet?
Windows 11 Pro is for people who also use their computer for work: it adds BitLocker, Remote Desktop and domain join. Windows 11 Home covers home use. The differences are explained in our comparison of the two editions. If you also need Office, the Windows 11 Pro + Office 2021 Pro Plus bundle costs less than two separate orders.
The key usually arrives by email within 15 minutes during working hours, together with an invoice.
