Windows 8 activation key lost?

I had bought lenovo ideapad s410 touch usually windows 8 already installed, i used an application downloaded from the internet and accidentally it changed my activation key to 1 month. I want to retrieve my original activation key.

If you bought the laptop from a retail shop or online genuine retailer like dell, Then you should see a label printed on the bottom of the laptop that looks like this:
Windows 8 activation key lost

This label will contain your genuine windows product key.

if you know that yours is geniune then you should run this program: https://www.microsoft.com/.../validate/