At first, Delete any old key (if there is a key in kaspersky)
B. Now, Disable Self Defense (Go to Settings, In Option, Turn off Self Defense and Click Ok )
C. Now, Goto Start menu, Click Run and Type "regedit". Go to :
HKEY_LOCAL_MACHINE\SOFTWARE\KasperskyLab\protected\AVP9\environment(For 32bit OS: - windows xp or vista or windows 7)
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\KasperskyLab\protected\AVP9\environment(For 64bit OS: - windows xp or vista or windows 7)
D. Now, Right look for PCID and right click and modify three or four last numbers or letters, a example is : (8F10C22F-6EF6-4378-BAB1-34722F6D454)and enter any other three-letter, four-number and close Registry Editor Now.
E. Go to Taskbar and Right Click the kaspersky Icon and click Exit.
F. Go to start programs and open kaspersky. when you activate searching trial license and you have a new license key for month.
G. Go to kaspersky settings and Enable (turn on) Self Defense.
After 30 days, when your license expire, go to step 1 to 7 and get a new 30 days license from kaspersky server automatically.
this is a tricks what is done a few minutes and give you a new trial license. so it is better to find a license key.