You are tasked with refactoring a legacy user validation process. Original Logic (Imperative Pseudo-code): 1. Check if user exists in DB. If not, return error 'UserNotFound'. 2. Check if user account is active. If not, return error 'AccountInactive'. 3. Check if user has premium subscription. If yes, grant access to Feature X. 4. If no subscription, check if free trial is available. If yes, start trial and grant access. 5. Otherwise, return error 'PaymentRequired'. Translate this logic into clean, functional Haskell code using the Maybe and Either monads to handle the error cases and the chaining of operations. Explain how the monadic binding handles the short-circuiting of errors.