A method, system and computer program product for preventing execution of pirated software. A file is loaded on an end user's computer containing a binary image that is generated by removing one or more code bits from an executable code. A request is sent to a remote server to return a software key required for execution of the executable code from the binary image. The software key is downloaded to the end user's computer on which the binary image is loaded. One or more bits from the software key is inserted into the appropriate location of the binary image to regenerate the executable code. The executable code is enabled for execution on the end user's computer only following the embedding of the one or more bits.