First Disconnect your Internet Connection.
Step 1:Click "License"

If you have old expired key, remove it before activate new one( "Click red 'X' button on key")
Step 2:
Click "Activate new license"

Step 3:
Enter Activation Code in Text Box and Click "Next"
(Download Activation Code) or get codes from here...

Step 4:
Now Error Massage displayed skip it and click "Ok"
Step 5:
Browse your downloaded key file
(Download Keys)

Now Your Kaspersky Internet Security 2010 activated.......
Click "Activate new license"

Step 3:
Enter Activation Code in Text Box and Click "Next"
(Download Activation Code) or get codes from here...

Step 4:
Now Error Massage displayed skip it and click "Ok"
Step 5:
Browse your downloaded key file
(Download Keys)

Now Your Kaspersky Internet Security 2010 activated.......
Reconnect Internet.......