So, you want to display on the ticket itself whether this customer have used some discount code and if they did, which one they have used. This add-on does just that. When installed and activated, it will add another ticket template element which, when placed to the ticket template, will display discount code (if any was used; if not, this area will be blank).
Add-on is installed and activated like any other WordPress plugin and works with Tickera as a "standalone" as well as when used accompanied by WooCommerce via Bridge for WooCommerce.