If your subscription is through Roku, you can generally only use it on a Roku device and if it's through The Roku Channel, you can generally only use it on a Roku device through The Roku Channel and not even using their Roku app. If you want to use a subscription on different devices, it's best to subscribe directly with the provider. If you can manage to sign in on Acorn's website, you should be able to use those credentials anywhere. If your subscription is through Roku, sometimes you can use your Roku account email address and the "Forgot password" option to get a password that's good for that provider.
