Plenty of script-driven apps, particularly paid content management systems, encode their files to make sure that they won't be reverse engineered or tampered with. Most of them use an application called ionCube PHP Encoder to do this, so, in case you obtain a paid script and you'd like to install it in a hosting account, a software tool known as ionCube Loader must be present on the server. Without this, you will not be able to install the script or in case you somehow manage to do that, it will not operate effectively for the reason that most of the script code will be encoded to a degree where it cannot be interpreted. That's why, you need to make sure that ionCube Loader is set up when you get a fresh hosting account and you'd like to take advantage of some paid web application. If you buy a shared hosting account and the instrument is not present, it cannot be added since your entire server PHP environment shall have to be compiled again.