Kindly note that the above operation is free of costs. Once your Business Profile is approved, you will start enjoying the advantages of the Free Listing. This means that your company will appear on a service port's page of your choice and a gray pin representing your company's location will be on the map.
However, if you want to further distinguish your business and stand out in the Port(s) you serve, there is the option of subscribing to a Promoted or Super Promoted Listing service and supercharge your business' visibility.
Each option unlocks even more features. For instance, while the Free Listing allows you to choose a single Serviced Port, the Promoted Listing allows you to choose up to three, and the Super Promoted Listing up to 10 ports.
You can find additional information here.