A free app for Android, by Greenled software.
Do you recognize this?
'Stay on' is a free, easy and ad-free app to extend the time your screen will stay on. It lets you stay on for a longer period of time, which can be very useful, especially when you're using a computer or a tablet with a limited amount of power.
Once you've installed the app, you can set the amount of time you want to stay on, which can be 30 minutes, 1 hour, or even 1 day. To restore your screen timeout, you need to click the icon again.
How does it work?
When you click the app icon, you should see a little message (known as a 'toast') which says "Screen timeout set to 30 minutes" and a notification-icon with a lightbulb will appear.