Lots of script-driven apps, particularly paid content management systems, encrypt their files so as to ensure that they will not be reverse engineered or tampered with. The majority of them use an application named ionCube PHP Encoder to do this, so, in case you buy a paid script and you wish to install it in a website hosting account, a software tool known as ionCube Loader needs to be present on your server. Without this, you will not be able to install the script or if you somehow manage to do this, it will not work effectively as almost all of the script code will be encrypted to a point where it can't be interpreted. In this light, you have to make sure that ionCube Loader is installed when you get a fresh web hosting account and you wish to use some paid web application. If you obtain a shared web hosting account and the instrument is not present, it can't be added as your entire server PHP environment shall have to be compiled again.