Let us have Plesk cGroups Manager out of the box
I think that with the price of cloudlinux being so cheap at 14$ per 1 license which includes the capability of using cGroups to manage resources, plesk should offer it out of the box and not on a paid extension because it's effectively cheaper to use cloudlinux for all the extra benefits instead of buying the hosting pack just for cGroups manager.
Please consider adding it as a permanent feature out of the box.
This functionality was added in Plesk Plesk Obsidian 18.0.41 (https://docs.plesk.com/release-notes/obsidian/change-log/#plesk-18041). We suggest you to upgrade and check it out.
Let us know if you have any feedback (https://talk.plesk.com/threads/cgroups-manager-is-now-a-free-to-use-feature.363772/).