Abstract: The present invention is a method and system for preventing and/or tracking unauthorized copying or distribution of downloaded software. In general, the software is tagged with user identifying and/or platform-identifying information, preferably in coded form, both to allow a validation check to determine whether a particular platform is authorized and to trace a pirated copy to its original authorized user. The platform-identifying information is preferably placed in numerous locations, some of which may be used for the validation check, others of which may not be. In addition, other information usable to identify an original user or purchaser may be embedded within the material of interest. Several alternative methods of tagging the software may be used depending upon whether the particular portion being tagged comprises executable or non-executable content.