Loyalty programs are widely used to increase customers’ repeat purchases and reward their continued patronage. Mileage is one of the most commonly offered loyalty program. Rewards such as mileage can build a customer’s loyalty and companies appreciate how valuable that loyalty can be. Although the understanding of mileage programs is important, little is known about how to apply. This research aims to find out better forms of mileage expiration messages with a customer’s mileage usage intention and message feeling to maximize customer’s loyalty. To verify the effect of mileage expiration message, we conducted an experiment in a 2×2×2 Design: 2 (message framing: positive vs. negative) × 2 (time pressure: high vs. low) × 2 (amount of accrued mileage: large vs. small) between subjects. Survey methodology is employed to test the hypotheses and there are eight types of survey questionnaires. Each subject was randomly assigned to one of the eight conditions. In this research, we found that customer’s mileage usage intention and message feeling play a critical role in enhancing customer loyalty. Second, with regard to three factors concerning a customer’s mileage usage intention and positive feeling, mileage expiration message with negative framing and high time pressure increases a customer’s mileage usage intention but decreases positive feeling, while mileage expiration message with a large size of accrued mileage increases both a customer’s mileage usage intention and positive feeling. Third, it is recommended to use mileage expiration message that increases customer loyalty. These findings suggest marketing managers to consider different types of mileage expiration messages and their effects.