@mkellyscgc
It depends on what Nest Aware subscription you have.
If you had a 1st gen (per-camera) Nest Aware subscription on a Google Nest Hello Doorbell and you bought another Google Nest Hello Doorbell, you'll probably need to contact Google Nest to cancel your old 1st gen subscription and add a new 1st gen subscription on your new Google Nest Hello Doorbell.
If you had a 1st gen (per-camera) Nest Aware subscription on a Google Nest Hello Doorbell and you bought either a battery doorbell or the 2nd Gen Google Nest Doorbell (which work only in the Google Home app), you can't use a 1st gen Nest Aware subscription, and will probably need to contact Google Nest to cancel your old 1st gen subscription and get either a Nest Aware or Nest Aware Plus subscription.
If you had either of the newer Nest Aware or Nest Aware Plus subscriptions on any Google Nest doorbell and you bought another Google Nest doorbell, the subscription should automatically cover the new doorbell, since these newer subscriptions cover all cameras and doorbells in the same Google Nest "home/community".
To contact Google Nest Support on this, you could try the "Contact us" link under "Nest Aware Premier Care" on the page below to "Get 24/7 access to Nest Aware Experts on the Nest Customer Care team. They’re available to answer questions, help you access features, and manage your subscription."
https://support.google.com/googlenest/answer/9233159
More info on subscriptions:
https://support.google.com/googlenest/answer/9681538
