Is a Prime Video title included, rented or sold through a channel?
Read the actual playback and checkout labels to identify included titles, rentals and add-on subscriptions.

Open the film or episode page. Look for the access label beside the version you want. Amazon distinguishes titles included with Prime from rentals, purchases and extra subscription offers. A result in the Prime Video storefront can represent any of those arrangements.
Check a single version all the way to checkout
Imagine a film appears in search and lists both an HD rental and an add-on service. Open the version you actually intend to watch. Compare the quoted one-time amount or recurring charge and the purchase account. A second family profile can have the title on its watchlist while your account still needs the corresponding access.
Keep the receipt or offer label
If you started a trial to see a specific series, retain the displayed subscription name, renewal date and billing account. If the offer was a rental, retain the rental terms shown for that title. This makes it easier to find the right account when the button changes or to cancel an add-on before renewal.