I saw lately in my competition's cpanel that they have some monitoring tool for each account in order to check CPU, RAM and I/O reseurces usage. Also to limit them. How can I do it? There is any tool for that?
The information you provided seems to match the features offered with CloudLinux, but I'd need to see a screenshot of the feature to verify that's the case. You can read more about using CloudLinux with cPanel & WHM at: