My operation system expire - Microsoft Windows Vista Home Premium Edition for PC

Subscription to what? If it's a magazine, the expiration date should be on the mailing label. If it's a website, you'll have to check with that website. If it's your FixYa membership, that doesn't expire.

Its illegal for anyone to provide serial keys for programs that have a retail value set on them.

Microsoft Windows requires an activate code when you install the operating system. This product key is evaluated each time the system is booted or when you decide to update the operating system critical files. If you installed an incorrect key or your machine's hardware changed significantly, the operating system prompts you for a valid key. If your product key has expired, you can contact Microsoft to purchase a new one. Enter a new key in the system settings in Windows to enable the operating system and continue using the machine.

Click the Windows Start button, then select "Computer." This opens your computer properties window. Click the toolbar item labeled "System properties." In the Window that opens, click "Click here to activate Windows now" and click the "Continue" button. This opens a dialog window with a product key text box. Enter your valid Windows product key and press the "Ok" button. Reboot the machine for the changes to take effect. The next time you boot, the operating system is activated and the error message no longer displays. Hope this helps.
http://www.microsoft.com/licensing/existing-customers/activation-centers.aspx

Microsoft Windows requires an activate code when you install the operating system. This product key is evaluated each time the system is booted or when you decide to update the operating system critical files. If you installed an incorrect key or your machine's hardware changed significantly, the operating system prompts you for a valid key. If your product key has expired, you can contact Microsoft to purchase a new one. Enter a new key in the system settings in Windows to enable the operating system and continue using the machine.

Click the Windows Start button, then select "Computer." This opens your computer properties window. Click the toolbar item labeled "System properties." In the Window that opens, click "Click here to activate Windows now" and click the "Continue" button. This opens a dialog window with a product key text box. Enter your valid Windows product key and press the "Ok" button. Reboot the machine for the changes to take effect. The next time you boot, the operating system is activated and the error message no longer displays. Hope this helps.

Microsoft security is an antivirus program. Yes, if the antivirus has expired it no longer protects the pc and it has became infected. No, it's not part of Windows, of any one of them. What you had it installed when you purchased was an reduced functionality one that was offered with a rebate and the licence for it has expired after an year.
Since the system is now fully infected you must uninstall the expired antivirus and install a new one. This one is free for home use
http://www.avast.com/free-antivirus-download

If you are talking about a Windows Operating System license key those do not expire. One thing that can happen is if you have used that copy of windows on a computer then bought/built another one then possibly another or on a friends what can happen is you run out of uses for that key. If that is the case you can call Microsoft customer service and they can clear the key's history for you allowing you to use again.

The only other thing I can think may be happening is either it was entered incorrectly or someone else is using your key? But as far as expiring its just not possible. (unless its not an Operating System key in which case please re-enter your question stating what product it is)

Can you be more specific on the download? is it operating system download or something else? wat is your operating system? xp, vista or 7?

You need to reinstall any other operating system.

If you have any imp. data then boot into safe mode, back up your data then reinstall windows

ok liscense doesnt expire you just need to register your system

vista will expire after 30 days if not activated

so u hav 2 ways one to buy the original key from microsoft or crack the os but its not ethical

CHECK THAT YOUR WINDOWS IS NOT PIRATED GET AN ORIGNAL COPY OF IT.