@sandra3030
Go to your Subscription Management page (https://store.google.com/subscriptions), click on your subscription, and then click on the "More" icon (the 3 dots); that should display a pop-up menu where you can select "Change your plan" or "Cancel subscription".
If you are still on a 1st gen Nest Aware subscription, I think you can still go to https://store.nest.com/account/subscriptions. (If we go there, we get forwarded automatically to the 2nd gen subscriptions page above because we're on a 2nd gen subscription.)
