Paid subscription for what? You don't pay anything for the Roku itself (other than the purchase cost). Roku has a search function, but it only works for providers that permit it to. If the provider doesn't allow Roku search, then it won't appear.
If you're referring to a search function within a channel that you have subscribed to, the provider of that channel would be who you need to contact for assistance.
Dan
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, just another user.