The first line of the APM log tells you when the APM ran and how it was started.
STARTING APM SESSION by AutopaginateDlg() at 02/Feb/2017 13:14:18.
Date and time
The date and time of the APM session is recorded on the end of the first log line
APM call mode
The APM call mode is displayed in the first log line after the fixed string STARTING APM SESSION by and it can be:
•AutopaginateDlg: the user displayed the Automated page make-up dialog box and then started the APM session.
•Autopaginate: the user clicked the APM icon on the toolbar and started the APM session based on the previously set context and preferences.
•AutoUnpaginate: the user held CTRL while clicking the APM icon on the toolbar and started the APM unlink editorial content session.
•AutoUnpaginateDlg: the user displayed the dialog box to unlink editorial content and then started the APM unlink editorial content session.