1. You receive Premium key look like: 688md7hp6cdfiqkdh

2. You should be log in at http://katfile.com/login.html

( Please register a new Katfile account, if you don't have an account )

4. Access "My Account" to activate your Premium key: http://katfile.com/?op=my_account

Enter Premium key in field with description "Apply Premium Key" and click "Apply" button