The rule of thumb for Google mobile products? Support major updates for about two years and security patches for another year after that. If the Google Store continued to sell the device a year past its debut, then patches would continue on 18 months from the time the store stopped selling it. By and large, the rule has been followed, though some devices have clung on for a major update or two past their prime.
If you thought for a second that Google would suddenly change things up and provide either less or more support, don’t think that anymore.
It hasn’t been a year since the phones’ launch, so for now, that last patch date stands, but you can now track that deadline to see if it moves on Google’s device support page.