How to activate Filefox Premium Voucher:
1. You will receive a Filefox premium voucher like this: 79xxdlnd5774la
2. You should be log in : https://filefox.cc/login.html
( If you haven't account at Filefox, you just need to sign up: https://filefox.cc/?op=registration )
3. Make sure you are logged in. Then access this link: https://filefox.cc/?op=my_account
4. Put your voucher code in field "Apply Premium Key", and click on "Apply"