If you install Windows 7 and if you not enter an installation key, the 30-day activation timer starts. To see how many days left, click Start, right-click Computer, and select Properties. At the bottom under Windows Activation, you will notice the days left in your trial period.

When that number gets close to zero, you can extend the free period another 30 days via the following steps:


Step 1: Click Start, All Programs, Accessories. Right-click Command Prompt and choose Run as Administrator.

type your administrator password.

Step 2: Type the following command and press Enter:

slmgr -rearm

Step 3: Restart Windows 7.

Once the Operating Systems reboots, the Properties dialog explained above will show that Windows 7's activation period has been rearrange to a full 30 days.