The session means the playback of watermarked stream content by end user. Unique watermark information (user ID, IP address, timestamp, etc.) can be entered as session data for each playback session. PallyCon cloud stores the session data transmitted through the session manager API, and embeds the ID of the data into the stream as unique watermark information. The monthly usage fee for the forensic watermarking plan is calculated based on the number of times the session manager API is called. And an additional fee for the pre-processing/packaging process is charged for each plan type.