Membership discount code

We are thinking about having a event discount code for a yearly membership fee that can be used for multiple events during that time. We will assign unique codes to each member to use at checkout. I see how to enter this in the contact and email fields but having issues finding a solution on event creation. 

When building an event Is there a way to enter a generic discount name that will prompt them to enter their unique code in another box to validate it? 

Thanks, 

Bonnie