Cross-site Lookup for SharePoint 2013 installation guide
Download setup file and run it on one of the servers in your SharePoint 2013 farm as Farm Administrator. Follow wizard steps.
Go to your application. Select Site Settings item in the root of the site collection. Choose Site collection features in Site Collection Administration section:
Activate Cross-site Lookup feature.
Now select a list or a library in the current site collection and choose List or Library tab in the ribbon. Here you can find a new Manage Plumsail Lookups button in Manage Views section: