Your comments

sorry, I did follow the step you told me, but at step 3, there is not an "academic account plan" at the bottom of the "Manage personal account plan" page.
could you please help me to change to academic account plan at the back or just close my account, so I can register again use this email address.
sorry,in "Manage personal account plan" panel, I do not where to complete a registration form
and I still can not find the Non-commercial plan option in the "Manage personal account plan" panel.