A lot of script-driven applications, particularly paid cms, encrypt their files so as to make sure that they won't be reverse engineered or tampered with. The majority of them use an application known as ionCube PHP Encoder to do this, so if you get a paid script and you intend to set it up in a website hosting account, a software instrument called ionCube Loader needs to be present on your server. Without it, you won't be able to install the script or if you somehow find a way to do this, it will not work properly due to the fact that most of the script code will be encrypted to a point where it can't be interpreted. In this light, you need to ensure that ionCube Loader is present when you get a fresh hosting account and you'd like to take advantage of some paid web application. If you get a shared hosting account and the tool is not present, it cannot be added as the whole server PHP environment shall have to be compiled again.