Complex sentence: One ship of no more than 500 tons could be sent to one of these places each year (the "Navío de Permiso") with general trade goods but one quarter of the profits were to be reserved for the King of Spain.
Split into simpler sentences: One ship of no more than 500 tons could be sent to one of these places each year (the "Navío de Permiso") with general trade goods. One quarter of the profits were to be reserved for the King of Spain.