Do I have to pay for Roku if I have a Roku TV?

Excuse me, I was wondering if I could clarify something about Roku and Roku TVs. If I already own a Roku TV, does that mean I still need to pay for any Roku services or subscriptions? Or is the Roku functionality included as part of the TV purchase? I'm just trying to understand the cost structure and whether there are any additional fees I should be aware of. Thank you for your help!