To enable the audit log by using Central Administration
· On the Central Administration home page,
· In the Application Management section,
· Click Manage service applications.
· Select the Secure Store service application.
· On the ribbon, click Properties.
· From the Enable Audit section,
· Click to select the Audit log enabled box.
· To change the number of days that entries will be purged from the audit log file, specify a number in days in the Days until Purge field.
· The default value is 30 days.
· Click OK.