I am already subscribed to Aeronautical Database but it seems that the database is outdated, what's the solution to this?

Make sure that you log in your account:  Configuration > Account.

iOS: Then check that the aeronautical database is up-to-date. Configuration > Store > Installed data > Aeronautical database > Update it

Android: Then check that the aeronautical database is up-to-date. Configuration > Installed data > Aeronautical database > Update it