1. You will receive a premium key like this: 359zn3cjo8ud7wl8i

2. You should be log into your account.

( If you haven't account, you just need to sign up free account: http://worldfile.net/?op=registration )

3. Make sure you are logged in. Then access this link: http://worldfile.net/?op=my_account

4. Paste your Premium key in "Apply Premium Key" and click "Apply" to proceed.