BMW E-SYS
E-Sys is a BMW engineering tool. Among other things, this means that it does not verify what you are doing and trusts you to know what you are doing. Be careful and make sure you understand what you are doing before doing it.
E-Sys is a BMW application. It allows you to perform a lot of operations as-is, but sometimes, it does not show information in an easy way. There are a lot of launchers that improve how information is presented and unlock many new features.
In order to get started and understand things you will not need a launcher. As you spend more and more time with the tool, if you feel like it, you may want to purchase a launcher. Among others, I would like to endorse the E-Sys Ultra launcher.