The Docs audit log allows administrators to see when users viewed or edited a document. These logs are available in the control panel under the Reports tab. Logging is disabled by default. It must be enabled in the Drive and Docs settings.

Note that changes made by APIs or views/edits to publicly accessible documents (which do not require authentication) are not logged.

Editions included
Google Apps, Google Apps for Business, Government and Education

For more information
https://support.google.com/a/bin/answer.py?hl=en&answer=2773649

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