Coupons are kept out of your site's search results by default, so in most cases there is nothing you need to do.
Coupon Creator automatically removes its coupon post type from the WordPress search query, which keeps individual coupon pages from showing up when visitors search your site. This is on out of the box.
If you actually want the opposite, and would like coupons to appear in search results, go to Coupons > Options > Display and check the Coupon Search option. Checking that box stops the plugin from modifying the search query, so coupons are included again.
Developers who manage search with their own code can adjust the list of searchable post types through the cctor_filter_searchable_post_types filter rather than using the option. The coupon post type name is cctor_coupon if you need to target it directly.
