@Theologos1
Have you tried to access your Premium Subscription through the Roku Channel?
Launch the Roku Channel and see if your subscription is in there. If you subscribe to a channel through Roku, generally, you have to access it through the Roku Channel. You usually cannot access it through the the standalone channel/app.
Which channel did you subscribe to?
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Otherwise, usually need to contact Billing/Accounts/Subscriptions at https://support.roku.com/contactus
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102