Yes, after that you either need to renew the subscription or you need to have enough crowns to open the areas again permanently.
If anyone is interested, I posted a breakdown of what all the chapters in the game cost in both crowns and real money (based on what size package of crowns you bought), as well as what the different subscriptions end up costing you. Don't mean to self-promote, but it seemed to relate. I had figured it our for myself, when I was trying to decide how much I would spend to play and looked at how fast I was going through the game and how long I indended to play. The link to my site is in the fan sites section under "Community". Hope this is helpful to anyone who was curious!
Host of the Talkin' the Plank Podcast, where we talk about Pirate 101 every Friday!