By default, plugin will add User ID on tracking link. In this way, admin can see which user made purchase and admin can gives him cashback.
But this is not single way to use Cashback Tracker. In some cases, you may need to give commission to author of post and not to users. For example, this can be helpful when you have Multi Author site and each author has access to admin pages and can use Content Egg, Affiliate Egg plugins or shortcodes of Cashback tracker. Now, you can enable option to assign Author ID to each link. Then, you can track which of your author makes the best posts and offers on your site and you can pay commission to authors from your affiliate sales.
Cashback Tracker ->
General Settinngs and select
"Author ID" checkbox.