If you have installed Windows 8 Developer Preview, the first thing you might want to do is activate it. Activation promises certain benefit, such as the ability to customize your lock screen and access additional services. There are two ways to Activate Windows 8, Metro or using the Classic interface. Lets start with metro.
On the Start screen, click on Control Panel
If you are connected the Internet, Windows will automatically begin the activation process. If not, click the Activate by phone link.
Classic Windows
Press Windows key + Pause Break key on your keyboard to take to the System Properties window. Or hover your mouse pointer over Start, click Search, enter system properties, click Settings to filter your search query and click the result.
Click Activate online.
Thats it. The new metro style is obviously much quicker, whichever method you choose, that’s how you can activate Windows 8.
Teching It Easy 
Well, I don’t actually see the request for activation on my machine. Perhaps it is due to the fact that I have made my PC connected to the Wi-Fi at home when I first started to run Windows “8” Developer Preview.
Hi Andre
I’d just like to ask if I should install Windows 8 on my main PC. I have a backup of the PC and also have a recovery disc. Is it worth giving a shot?
Can I rollback if I want?
Would appreciate a detailed answer if you understand my worries!
Thank you
it says this pre released version of windows has expired. your computer will restart every two hours and you might lose any unsaved data.
How to activate windows 8 pro on a new hdd(replaced old) or when changed CRT-monitors to touch screen? In Microsoft Answers, we find everywhere “Contact Support person through Phone Activation”. But many people say in different sites/blogs/forums that this didn’t help, tried many times. I don’t want to have a system image because, i don’t want to buy another hdd for the backup image and i don’t have much size on my network/cloud storage. And this image thing is problematic as it sometimes makes drive un-bootable/doesn’t activate properly. If this happens, how to activate the windows 8 pro?
Activation is taking a long time. Its over half an hour
Try the following:
Press Windows key + X
Click Command Prompt (Admin)
Type the following commands:
ipconfig/release
Hit Enter
then
ipconfig/renew
Hit Enter
then
ipconfig/flushdns
Hit Enter
Exit command prompt and try activating again.
If the problem persist, try the following:
1. Press Windows key + X then clickRun, then type: slui.exe 4
2. Next press the ‘ENTER’ key
3. Select your ‘Country’ from the list.
4. Choose the ‘Phone Activation’ option.
5. Stay on the phone (do not select/press any options) and wait for a person to help you with activation.
6. Explain your problem clearly to the support person.
Adacosta excellent answer. I used it but I put the number 3 instead of 4 because I needed to change the product key number. Thanks
Hi, I cannot activate window 8 even if am connected to the internet. What’s the problem?
Try phone activation:
1. Press Windows key + X then click Run, then type: slui.exe 4
2. Next press the ‘ENTER’ key
3. Select your ‘Country’ from the list.
4. Choose the ‘Phone Activation’ option.
5. Stay on the phone (do not select/press any options) and wait for a person to help you with activation.
6. Explain your problem clearly to the support person.
I just install windows 8 on my pc but the problem is that I do not know how to activate
i just install windows 8 on my pc but the problem is that I do not know how to activate
my problem is that I don’t have the code for activating it, it doesn’t show up on the box
Hi, I just downloaded windows 8 and updated my computer from windows 7. The update went smoothly and I am able to use my computer. However I can’t really do any customizing. When for instance I click on my name and Icon to change my picture, it gives me a notice in red to activate windows 8. I go back to my change computer settings and found ‘activate windows 8’ i click on that and i simply says “Thanks, you’re all done!” This isn’t the case tho cause I still can’t customize my settings and in changing something it still gives me the first message.
slui.exe ! That did it for me, thanks!
I just bought a brand new PC and it has Windows 8.1 already installed it says windows activation complete but I can’t access screen lock setting and other various personalizing options.
Restart the machine, if the problem persist:
Perform SFC Scan
Please follow the steps to perform SFC Scan:
a. Press “Windows Key + Q” to open Charms Bar.
b. Type “cmd” without quotes in the search box.
c. On the left pane, right click on the “cmd” option and select “Run as Administrator”.
d. Type ‘sfc /scannow’ without quotes and hit enter.
Note: It may ask for windows installation DVD to fix and to enable SFC to make more than minor repairs. Some files saved on your computer might get deleted when fixing corrupted files.
it says no key management service contacted
1. Press Windows key + X then clickRun, then type: slui.exe 4
2. Next press the ‘ENTER’ key
3. Select your ‘Country’ from the list.
4. Choose the ‘Phone Activation’ option.
5. Stay on the phone (do not select/press any options) and wait for a person to help you with activation.
6. Explain your problem clearly to the support person.
If the problem persist:
Perform SFC Scan
Please follow the steps to perform SFC Scan:
a. Press “Windows Key + Q” to open Charms Bar.
b. Type “cmd” without quotes in the search box.
c. On the left pane, right click on the “cmd” option and select “Run as Administrator”.
d. Type ‘sfc /scannow’ without quotes and hit enter.
Note: It may ask for windows installation DVD to fix and to enable SFC to make more than minor repairs. Some files saved on your computer might get deleted when fixing corrupted files.
please i want to activate my windows 8 but don’t have any activation code or so. I bought the laptop just about a month ago.