Hello,
Thank you for your question on a RAM usage statistics tool in cPanel. Currently there is not a native monitoring tool that displays the RAM usage of cPanel accounts. You can use the 'top' command when logged in to SSH to see current RAM usage in percentages. That may help you, depending on what you are looking for.
We do have some upcoming developments that will ultimately allow you to monitor resources like this from within your AMP, though there is no release date set for that as of yet.
Kindest Regards,
Scott M