Hook from redirect to page

That's a completely different message. For some reason you are creating a infinite loop of redirects. You need to start removing some code and see where it always returns true (or false) and keeps redirecting the user.
If the problem gets solved by just removing "redirect('admin/index','location');" you are always returning false on "$this->CI->session->userdata('paid')" and you should stop checking for it in admin/index.