If you're running the trial version of KIS, the key to which is given at 1 month, 3 months, 6 months, extend it is possible. Moreover, there are 3 ways to do it.
The first way is at the end of the trial to completely reinstall the operating system on your computer, including cleaning the registry, and then activate a trial version of KIS again. It's tedious, time-consuming, but it is legal.
The second method is to access the infinite resources of the great and mighty Internet. But there is one "BUT". In fact, you will become an illegal user of the product, so as to extend the trial license is only possible by using pirated software-hackers. Kaspersky lab is currently conducting serious work to identify burglars. And one day it may happen that you have installed on your computer "eternal" trial keys will be completely blocked, nothing will help even re-installing.
The third way is to go to the website and choose a suitable offer at an affordable price. The license is valid for 1 year, then assumes the extension of the license. The renewal price in the current economic conditions - is purely symbolic.