1. Please login to your DataFile account first: https://www.datafile.com/login.html
( If you don't have an account, please register an account )
2. Then, access this link: https://www.datafile.com/getpremium.html
3. Find this text "If you have invite code", then click to "Click here"
"Premium Key" tab will be appeared, paste Premium Key to "Invite code", and click ACTIVATE