Hidden security feature on Samsung Phones.
Smart Lock
Now you don’t have to unlock your phone everywhere.
To find Smart Lock, you first need to set up a secure lock screen option (Pattern, PIN, password, fingerprint etc.) by heading into Settings>Lock screen. Once you have done that, you need to back out to Settings, and then head into Security. Within the Security screen, tap on Trust Agents, then turn on Smart Lock. From here, you can backup once and you should now see Smart Lock as an option at the bottom of the screen in the Security section. You are now ready to start adding trusted devices and places.
And also..
http://www.droid-life.com/2015/02/03/how-to-enable-lollipops-smart-lock-in-touchwiz-on-the-galaxy-s5///cdn.embedly.com/widgets/platform.js