Abstract: An apparatus for preparing and playing back a duplicated disk containing software as a program so that a customer will be able to use the disk for a predetermined trial period. The duplicated disk is impressed with information relating to this system in the form of a usage count, a locking status and an output code. The usage count is written on the disk and determines the number of times the disk can be used by a customer. The output code identifies a locking code whereby after the allocated number of uses is over, the vendor can unlock the disk to allow unlimited use. The lock code determines whether or not the disk is subjected to the above noted trial usage period. The usage count which is impressed on the disk is detected during each time the disk is used and the usage count is decremented by one until the predetermined number of uses has been accommodated.