What do you mean by "I pay for service"? There is no Roku service, but there are lots of scams. Individual channels/providers may charge for service (Netflix, Hulu, etc.).
What do you mean by "sync the two together"? Any subscription paid through Roku should work on any Roku device linked to the same account. Subscriptions paid through the provider (e.g., Netflix) should have a way to authenticate on any device, Roku or otherwise.
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