The Federal Trade Commission’s rule to make it easier for consumers to cancel subscriptions is already facing a legal challenge. The final “click-to-cancel” rule was announced last week and industry groups representing companies that rely on subscription revenue filed an appeal on Wednesday, Oct. 23.  Click-to-cancel requires retailers, gyms and other subscription-selling companies to make cancellation “at least as easy” as it is to sign up. The rule will also require companies to document consent from customers for subscriptions, auto-renewals and free trials that turn into paid memberships. “It was very clear that something needed to be done to protect…