A lot of script-driven applications, especially paid cms, encode their files in order to make sure that they will not be reverse engineered or tampered with. Most of them use an application known as ionCube PHP Encoder to do this, so, in case you buy a paid script and you intend to install it in a web hosting account, an instrument called ionCube Loader needs to be present on the server. Without it, you cannot install the script or if you somehow find a way to do this, it won't work properly as almost all of the script code will be encrypted to a degree where it can't be interpreted. In this light, you should ensure that ionCube Loader is set up when you get a fresh web hosting account and you want to take advantage of some paid web app. If you buy a shared hosting account and the tool is not present, it cannot be added as the entire server PHP environment shall have to be compiled again.