The Nest Secure security system comes with two Nest Tags, which can be used to quickly arm and disarm the system. However, they can easily get lost, so here's what you can do if that happens.
A Nest Tag is about the size of a half dollar coin, but it has the addition of a small rubber loop that lets you attach it to your keyring. Still, though, with something so small, it's bound to get misplaced at some point, especially if your teenager has one.
Unfortunately, Nest doesn't have any kind of "Find My Nest Tag" feature where you can locate a lost Tag, but you can at least disable it remotely so that if someone else gets a hold of it, they won't be able to use it to disarm your system.
Open the Nest app on your phone and tap the "Settings" button (the gear icon) in the top right corner of the screen.
Tap the "Security" option at the bottom of the list.
On the "Security" page, scroll down to the bottom and select the Nest Tag that is lost.
If you think you'll find the Nest Tag eventually, tap on "Nest Tag Access".
From here, you can disable the Nest Tag from being used by tapping on the toggle switch, but it will still be attached to your Nest account.
If it's a lost cause and you think the Nest Tag is gone for good, you can tap on "Remove Nest Tag" at the bottom.
Tap on "Remove" when the pop-up appears to confirm.
As it says in the "Nest Tag Access" menu, that person who lost their Nest Tag will still be able to arm and disarm the system using their passcode---they just will no longer have the convenience of the Nest Tag until it's replaced with a new one.