I saw that comment too and I am still trying to figure out what is IAP. The only thing I can find with Google and "baldur's gate 2 iap" is this story and quote
Baldur’s Gate II: Enhanced Edition coming soon to iPad… with IAPs
Wednesday, January 8, 2014
Baldur's Gate 2 Enhanced Edition iPad Android tablet screenshotWe were keeping our finger crossed when Baldur’s Gate II: Enhanced Edition was submitted to Apple a month ago, but it didn’t help. The game was refused by Apple’s submission team once or twice, but according to Beamdog’s Trent Oster, the wait is almost over. Apparently, the game’s in-app purchases have been approved and… wait, what?
Yeah, it turns out Baldur’s Gate II: Enhanced Edition will feature IAPs on iPad and (eventually) Android tablets. This honestly isn’t a huge surprise, as we’ve predicted something like this will happen way back in August when it was announced that the remake will feature four new characters with unique quest lines, but it’s still a shame that a $15 mobile game will have paywalls.
Which would seem to say that the original game/story is there for $15 but you can get 4 new characters with unique quests for IAP.