I have configured a IIS Web server correctly, however i have a problem that the windows service keeps stopping after a few hours of not using it. I have i configured something wrong in the application.conf or is it something to do with the key.mx because i don't seem to have that file. Also when i run the website it still says that it is in development mode.
Yes, you'll need a key for Mendix to keep running continuously, otherwise the server will indeed stop after some random amount of time. If you don't have any, you should contact Mendix about the licensing options.