MOLPRO is distributed to licensees on a self-service basis using the world-wide web. Those entitled to the code should obtain it from http://www.molpro.net/download supplying the username and password given to them. The web pages contain both source code and binaries, although not everyone is entitled to source code, and binaries are not available for every platform.
Execution of MOLPRO, whether a supplied binary or built from source, requires a valid licence key. Note that the key consists of two components, namely a list of comma-separated key=value pairs, and a password string, and these are separated by `&'. In most cases the licence key will be automatically downloaded from the website when building or installing the software.