This paper incorporates a durable-good monopoly model and re-examines the argument on licensing contracts. It shows that, from the perspective of the non-producing patent holder, the optimal licensing contract depends on the nature and the degree of the innovations. Specifically, for small cost-reducing or quality-improving innovations, charging a royalty is optimal. For large costreducing or quality-improving innovations, licensing by means of a fee and a royalty is superior to using either alone. However, for the case of horizontal product innovations, using a fee contract is optimal.