help_paramountplusappletv,
Thanks for the reply, and additional information regarding your Apple TV and Paramount + subscription.
A subscription would be associated with the Apple ID which signed up for it. If you have multiple Apple IDs associated with your Apple TV, then being signed in to an incorrect Apple ID could explain why this happens.
Set up multiple users on Apple TV
Here's more info about using the Apple TV app on Apple TV:
Subscribe to Apple TV channels in the Apple TV app
If you can't watch or stream movies and TV shows in the Apple TV app
If you're using the same Apple ID in the Apple TV app, Paramount +, but still are getting the purchase prompt, we'd recommend contacting the app developer:
How to contact an app developer
If you've been billed for watching a show, here's a resource that can help:
If you see "apple.com/bill" or an unfamiliar charge on your statement
If you need further assistance, then please reach out to Apple Support: Get Support
Cheers!