settings.lua stores info in a local file. 

Do this somewhere in main():

settings.load()

Then you can get values easily:

local soundOn = settings.get('sound_on')
if soundOn then
  print("Sound is on")
else
  print("Sound is off")
end

You can also set values easily:

settings.set('sound_on', false)
settings.set('music_on', true)

The info will be saved to a file as soon as settings.set is run.
The info will persist across the application restarts.

Thats all!