How to secure PostgreSQL Data for distribute?

Dear All,

 

     I need to distribute my application that use PostgreSQL as database to my customer. But I still have some questions in my mind on database security. I understand that everybody  who get my application database will be have a full control permission on my database in case that PostgreSQL already installed on their computer and they are an administrator on PostgreSQL. So that mean data, structure and any ideas contain in database will does not secure on this point. Is my understanding correct?

 

     What is the good way to make it all secure? Please advise.