How to install a new key file: 
  • open Kaspersky Anti-Virus 6.0 or Kaspersky Internet Security 6.0 main application window 
  • go to the Service tab
  • left-click the License Info section
  • in the open window click the Activate button 
  • in the Setup Wizard window select Apply existing license key 
  • click Next
Note: if the currently used key file for Kaspersky Anti-Virus 6.0 or Kaspersky Internet Security 6.0 is still valid, the corresponding warning window will be displayed. 
  • in the Activation window click the Browse button 
  • select the folder in which you unpacked the contents of the received archive with the key file/ saved the key file 
  • double-click the key file 
  • see the information about the added key file and click Next 
  • in the last Activation window click Finish 
  • close the window with the info about the used license keys 
  • minimize the main window of Kaspersky Anti-Virus 6.0 or Kaspersky Internet Security 6.0

Note: the dialog windows in the article are given for Kaspersky Internet Security 6.0. The dialog windows forKaspersky Anti-Virus 6.0 product are the same, but for the name of the product.