Powerful domestic tool, translated into 37 languages: just embody in-purchase and earn.
Make it freemium. Just implement in-purchase and let the user open additional options for money. Or earn on the ads. Also you'd better to redesign the app, b/c it has default UI.
For sale: source code of the app and the app transfer.
First, what you need to do - it's implement in-purchase and let users to buy additional features:
1. Range of turn off = 1$.
2. Allow to switch on flashlight and screen light at the same time = 1$.
3. Different colors of screen light = 1$.
etc.
Also you can earn on the ads.
Another way - is to enable all features for a week as a demo and close most of them, until user pays.
The app Night Lamp turns any phone into a voice-activated lamp.
Especially recommended to try option when activated simultaneously flashlight and the screen, and on the screen is a smooth transition of colors.
So, it'll take a week or two for you to embody all suggestions and you will start to earn after that.
Text me, if you want the app with transfer. I'm selling all my 30 apps, developed in 4 years, b/c I'm changing field of activity. Check all my listings.