If you install Windows 7 and don’t enter an installation key, the 30-day activation clock starts. To see how many days you have left, click Start, right-click Computer, and choose Properties. At the bottom of the dialog under Windows Activation, you’ll see the number of 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....
