If you would like to promote your events using a discount code (promo code, coupon code) you can now purchase an extension for Registrations for the Events Calendar Pro that allows you to do just that.
Create and edit discount codes from the WordPress dashboard. You can restrict discount code use to specific events or event an event category. Set an expiration date or restrict use to specific venues and tiers.
This will be the first a few extensions available for purchase for users that need more advanced features for payment collection.
View the product page and purchase this extension by clicking this link.