Adding devices to Ring Alarm with Protect Plus

We have had our Ring Alarm installed for some time, and have added devices to it since initial installation. When it was first installed, we had the benefit of a free-trial period (1 month) of Ring Protect, to which i have subscribed to, and paid from month 2.When addidng small devices like contact or motion sensors, i never gave it any thought, but i have now purchased a Floodlight Cam Wired Plus, and will be adding it to my set up, reading the blurb that comes with it, if i were to have purchased it as a non subscriber, i would get 1 month Ring Protect free, however adding to an existing system and subscription, it appears that it is covered, and no free period benefit.Is this right? Apologies if this has been asked/answered in the past, butni havent found the answer by searching precious posts.