Go to Settings -> All (tab) -> Security -> Smart lock. This function allows you to add a convenient lock feature that keeps your phone unlocked in certain specified conditions.
  • Trusted devices: When one of your paired trusted devices is in proximity, you may add the Smart lock function at this setting to keep your phone from locking as long as it’s paired with the device.
  • Trusted places: You can add a trusted place such as your home or workplace to keep your phone unlocked in these locations. (Note that your phone’s GPS must be enabled to allow this feature.) To add a trusted place, click on the “Trusted places” option, the click “Add trusted place”. You can either type in an address in the search bar to select that location, use your current location, or use Google Map to select a location. The blue dotted circle indicates the proximity range the Smart lock function will be in effect.
  • Trusted voice: You may add a variety of voice recognition features in this option. You can train your phone to recognize your voice model with this feature.
    • From the Google app: You can say “Ok Google” to start a voice search from the Google app.
    • From any screen: Turning this option on allows you to voice your commands to your phone. You can start by saying “Ok Google” while either the screen is turned on or your device is charging, then give it a command, such as “Call (Name),” or Open (application).
    • Trusted voice: By turning on this function, you can unlock your device by saying “Ok Google.” Your phone screen will then unlock if the sound matches your voice model.
  • On-body detection: After unlocking your phone once, this feature keeps your device unlocked while you’re carrying it in your hand, pocket, handbag, etc. until it is set back down. However this feature can’t always distinguish between you and someone else. If someone takes your device while it’s unlocked with on-body detection, they might still be able to access it.