An increased audit capacity for Ops Center is something that folks have been asking about for a while. In 12.2.1, we added audit logs to provide this capability.
The audit logs are kept on the Enterprise Controller system starting in 12.2.1. They contain records of user logins, changes to user accounts, and job details. The logs require root access on the EC system and can't be edited, so they're a secure means of tracking who's logged in to Ops Center and done what.
The Feature Reference Guide has more information about how to view the audit logs.