Step3:Now exit Kaspersky Internet security/Antivirus 2010,by right clicking the Icon of kaspersky Internet Security/Antivirus 2010 in the taskbar.
Step4: Open Run(Windows key+R),then type regedit and then press Enter.
Now registry editor will open.Now browse to HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\KasperskyL ab\protected\AVP9\environment(Windows7 x64) ; HKEY_LOCAL_MACHINE\SOFTWARE\KasperskyLab\protected \AVP9\environment(Windows7 x86)
(Note:For other versions of Windows, this path might be different)
then select PCID & modify it.After that close registry editor.
Step5:Open kaspersky Internet security/Antivirus from the start menu. It will prompt to activate license.Click on Activate Trial Version. All done!!!