It's far too easy to subscribe to a channel/app both through Roku and directly with the provider as it appears you did. If you cancel your Roku subscription it will still be valid until the end of its current period. You may want to wait for that to happen and then get things working with your Motortrend subscription. I'm not familiar with that channel/app, but in general when you first launch a channel/app it will ask you to sign in or subscribe. In order to get back to square one so that it looks like it's the first time you launched the channel/app you have to remove the channel/app, restart your Roku, and after it has restarted add the channel from Streaming Channels. You can't remove a channel if you have an active subscription through Roku, but once you cancel it you can.
You can view and cancel your Roku subscriptions at:
https://my.roku.com/account/subscriptions
Roku Community Streaming Expert
Help others find this answer and click "Accept as Solution."
If you appreciate my answer, maybe give me a Kudo.
I am not a Roku employee.
