Install the Enterprise Search Audit App
Installing the Enterprise Search Audit app.
Your administrator must enable Search Audit from Administration > Security > Policies before you can install this app.
To install the app 
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From App Catalog, search for the Enterprise Search Audit app.
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Click Enterprise Search Audit.
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Click Add to Library, this will open a window. Within the window click on Advanced and choose a location to install the app.
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Choose a location for Enterprise Search Audit in your Personal folder.
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Click Add to Library. A dialog will confirm the app is installed successfully.