Patent ID: 8474055

Claim:
A method of managing digital content generated by applying digital rights management (DRM), the method comprising: confirming, in a client computer, whether or not the digital content is in a first period in which the digital content can be normally executed; and if the digital content is in the first period, normally executing the digital content in a first execution, and if the digital content is in a second period which is not in the first period, executing the digital content in a second execution, wherein the first and the second execution are different; wherein if a valid period included in contents of a license for the digital content includes a condition period and a grace period, the first period is the condition period and the second period is the grace period, and wherein execution of the digital content is prevented if the digital content is outside the valid period; wherein if the digital content is in the second period, providing a message indicating that the valid period approaches expiration; wherein the message comprises information regarding at least one of restricting reproduction of part of the digital content and lowering quality of all or part of the digital content, and wherein the information comprises at least one of an information item on a playback position and a size of the part of the digital content that is not reproduced, and an information item indicating a degree to which the quality of the digital content is lowered.