I just changed my email on one account (with a lvl 64 rogue), and it asked me to activation that account. After I activated it, I recieved 3 days of free premium. So I tried it again. I changed the email again, and activated the account again. 3+3 days = 6 days.
This thread is not for abusing the premium bug, but it is for "education purposes" .
What do you think about this people? I really want to know.