Upon retiring from your career as a pirate, your exploits will be calculated together as a single Score. This score is then compared to the maximum score achievable in the particular version of Pirates! you are playing, and based on the result the game will determine which job or profession you will have in your post-pirating days, presumably for the rest of your life.
This chosen profession will be shown visually, as a picture of your character at his job. This picture appears at the very end of the retirement process (assuming you chose not to continue your adventure, if given the choice at all). It serves as a visual measurement, and a bragging-rights reward.
In Pirates! (1987), the "maximum score" with which your exploits are compared is 100 Pirate Points. However, you can end up scoring less than 0 points, or more than 100 points, depending on your achievements.
Sid Meier's Pirates! (2004)Edit
In Sid Meier's Pirates! (2004), your score at the end of the game is equal to the number of Fame points you've accumulated. It is always visible on your Personal Status page, where it is referred to as "Achievement Points".
The score in this game ranges from 0 to 126, and can never be outside this range. Your chosen post-retirement profession is based directly on the number of points you have when you decide to retire for good.