This paper studies the incentive of a long run seller to disclose past offers when trading with a sequence of short-run buyers. Compared with the models of mandatory disclosure or mandatory non-disclosure, there is a new set of equilibria generated by allowing exibility in the disclosure option. In this new class of equilibria, the seller adopts a threshold rule in disclosure and only discloses rejected price offer above the threshold to the future buyers. In a two-period case I show that the welfare-maximizing equilibrium in the optional disclosure model could generate a strictly higher surplus than any equilibria in models with mandatory disclosure restrictions. Moreover, a policy maker can adopt non-disclosure policy for lower prices and voluntary (or mandatory) disclosure policy for higher prices to enhance trading efficiency, which is also reflected in eBay's disclosure policy of past transaction prices.