Add a file path to an addon

I would like to add a file path to an executable in my addon which can’t be hard coded (it’s different for every user depending on operating system and local folder structure). I’ve seen this done before, but I don’t know how.

It should look kind of like this:

edit: Never mind, found the solution myself. Sorry for jumping the gun. Feel free to close this thread.

Be aware that addons preferences are not persitent if you unload the addon.