The OCI Audit Log allows admin users to view the historical activity for an individual OCI. The audit log is best used to answer questions on the timeline of admin actions taken on an OCI. Please note that the audit log is currently in Beta, and as such, not all actions may be recorded in the audit log.
From the OCI posting, click on the Action button, and select View Audit Log (Beta)
The Audit Log will contain a timestamp, name, user type details, the action, and details on the affected fields