Unlimited Pirate life:
Successfully complete all ten pirate quests. The game will ask if you want to retire or not, choose "Retire". When asked to return to the sea or not, choose "Return to pirates life". Save the game in the current town. Reset game and then load the saved game. Notice that the year and your age reset, but everything else is the same. However, everyone in town thinks you are a pirate and you cannot purchase anything or save. Leave the town then quickly return. Notice that you can now save the game and everyone is normal again (but your age and year remains reset). This allows you to be an ageless pirate.

If you want to repeat this trick, follow these steps. Go to the cabin, highlight the mirror, and click on it. Choose to retire first, then when asked if you want to return to pirate life choose "Yes". Save the game and reset. Load the game you just saved, and the years should turn back. Do this every time you want to be a young pirate again.