You can cancel your subscription at any time directly from the Meter app.
Steps to Cancel Your Subscription
Open the Meter app on your device.
Tap on the Settings tab at the bottom of the screen.
Scroll down and tap Manage Subscription.
Follow the instructions to cancel your current plan.
Once canceled, your subscription will remain active until the end of the billing period. You won't be charged again unless you choose to resubscribe in the future.
If you don't have access to your device
Apple App Store: https://support.apple.com/en-us/118428
Google Play: https://support.google.com/googleplay/answer/7018481