1. A system for on-demand distribution of data files over a communications network, comprising: a memory; a processor in data communication with the memory; a network interface in data communication with the processor; at least one catalog stored in the memory; wherein the at least one catalog is configured to reference at least a first data file and a second data file, wherein the first data file comprises at least a portion of a first work, wherein the second data file comprises at least a portion of a second work, wherein the first work is different from the second work, wherein each of the first data file and the second data file is capable of transmission to a user device over the communications network, wherein each of the first data file and the second data file is selectable by a user from the at least one catalog, and wherein either: the first data file and the second data file each comprises at least one musical recording, or the first data file and the second data file each comprises at least one moving image; and wherein the processor is configured to: require at least a first authorization in order to permit at least one of transmission or play of at least a portion of each of the first data file and the second data file, wherein the first authorization is configured to expire if a predetermined act is not performed by or on behalf of the user on or before a predetermined date, which predetermined date comprises at least one of a predetermined calendar date or passage of a predetermined period of time, wherein the first authorization is usable across at least two logon sessions prior to the predetermined date, and wherein the at least one of transmission or play of at least a portion of each of the first data file and the second data file is at least one of limited or inhibited after the expiration of the first authorization; require at least a second authorization in order to permit play of at least a portion of at least one of the first data file or the second data file, wherein the second authorization comprises decryption data; and generate at least one instruction to transmit to the user device at least a portion of at least one of the first data file or the second data file.