If I am developing an app that has a 30 day trial, for example, where would the best place be to store the license information? Application support is too easily accessible, but I am not sure where else would be appropriate...
ApplicationSupport or Preferences is the correct place for it. If someone deletes the appropriate file to get an extra 30 days of use, is that such a big deal?
If you really want to stop people from getting more than 30 days of use, consider online activation.
You could also require Admin access to install your app and put a hidden file somewhere deeper in the system, but that would definitely fall under bad practises.