Allow ACEweb registrants to use 'one-time' coupons, i.e. the registrant can use the coupon discount on one course only in a given term.
Set up the One Time Coupon details in Pay Preferences. In this example, registrants using the ONETIMEC coupon code would get $25 off one Spring 2012 registration (e.g. a course that starts with 12S):
When the registrant adds the course to their Cart, they get the chance to enter the coupon (promotional) code: