Activity unified interface and logging are available under the "Filigran entreprise edition" license.
OpenCTI activity capability is the way to unified whats really happen in the platform. In events section you will have access to the UI that will answer to "who did what, where, and when?" within your data with the maximum level of transparency.
By default, the events screen only show you the administration actions done by the users.
If you want to see also the information about the knowledge, you can simply activate the filter in the bar to get the complete overview of all user actions.
Don't hesitate to read again the overview page to have a better understanding of the difference between Audit, Basic/Extended knowledge.