I unsuspended your account.
Make sure that you login to forums(here) atleast every 31 days to avoid inactivity suspension. Login to Account Panel or Cpanel doesn't count as activity.
Yes,
Once you purchase the Premium hosting
You have to post a support ticket in Client Area with the details of your hosting account like cpanel username....
Then the staff will move the hosting account manually from free server to Premium server.
Mostly the scripts causes the high resource usages are some plugins in wordpress like Google Sitemaps, MySQl backup
So disable all the plugins, enable one by one and check which one is causing it.....