The Inaction Intertia Effect states that when users don't take an opportunity to gain value or accept an offer, they are less likely to get it the second time.

This could be related to the Cognitive Dissonance theory, which states that users want their actions to be consistent with what they already did.

One important way to apply the effect is don't offer the same discount to people twice, rather switch it up and offer a new one

The less you price something the less valuable it seems to people so be sure not to charge too low