Lifekey uses the same technology your use to pay with your phone (Apple pay, Google Pay, etc..). With and NFC enabled phone, unlock or "wake" your device and tap the top back of your smartphone to the Lifekey device. You may need to touch the two devices together momentarily for the signal to be picked up by your phone.
You DO NOT need an app to scan a Lifekey device unless it's an older iPhone (released before 2017). Otherwise, most modern phones will work straight away.