jackgolding parent
Market research is the easiest way to solve these problems!
What if you provide a discount code in the ad that’s unique to the ad? Subsequent ads have slight lower discounts so there’s an incentive to use the code from the first ad they saw.
Discount codes was one method used, the only problem was that at the $1000+ ticket level, it's often another department buying the tickets and they frequently don't bother to use the codes :-D
Might work for some people, but the probability that I would even remember the first ad had a code - let alone the exact string - is minuscule.
Not being able to find a discount you saw can be pretty frustrating. Less important in this case as employers often pay for these conferences.