The iPhone7 is super awesome, but because of its water resistant coating PopSockets sometimes have a hard time sticking to them.
We've found a solution though! Press the PopSocket firmly to your phone and hold for at least 10 seconds. Now, we know that Popping is irresistible, but you want to resist it for at least 8 hours! The gel will adhere more securely as it rests and you'll be good to go.
Please bear in mind that PopSockets are only recommended as as an aid to holding a device only when the device is otherwise securely supported.