Lianja includes PHP, Python and JavaScript as part of the distribution as these are embedded in the App Builder.

PHP is located in:
C:\lianja\scriptinglanguages\php

The PHP configuration file is located in:
C:\lianja\scriptinglanguages\php\conf\php.ini

You can also set the include_path in php.ini. It is currently commented out and defaults to the current app directory. You can therefore reference php libraries relative to the app like this:
include("..\libraries\myphplib.php")