Knowledge trading through online paid-knowledge platforms (i.e., knowledge monetization) has enjoyed tremendous growth in recent years. As experience goods, knowledge products often suffer from low sales due to information asymmetry. Therefore, some platforms have launched free return policies as post-purchase warranties to reduce uncertainty and stimulate sales. The impact of free returns on knowledge product sales is explored. Using data from a Chinese paid-knowledge platform, the results suggest that a free return policy negatively influences sales. Also, this relationship is weakened by information richness of extant reviews. The findings contribute to the literature and help platforms design optimal return policies.