Home Screen and Lock Screen widgets, along with Apple Watch complications, require Tide Guide Pro. They can show tide progress, upcoming tides, marine conditions, and Sun or Moon information without requiring you to open the app. What you see depends on the widget, complication, station, and provider.
A lock means the widget or complication does not currently recognize active Tide Guide Pro access. If you already have Pro, restore your purchase on iPhone at Settings > Support > Restore Purchase, or on Apple Watch at Settings > Pro > Restore Purchase. Then open the Watch app once to sync your access and current station. Restoring a purchase will not charge you again.
iOS and watchOS control when widgets and complications refresh, so the lock may not disappear immediately. If it remains after Pro has been restored and the apps have synced, reopen Tide Guide or contact Support.