My brother & sister-in-law have an NCL Baltic cruise booked. They just received a $500 charge on their account to cover "service charges" for the "free" beverage package they selected. They decided it wasn't worth it and cancelled the drink package. NCL's initial response was that it was too late to cancel even though the cruise is over 2 weeks out. NCL reversed that when it was pointed out that their own written policy is that only 48 hours notice was needed.
Makes me wonder if any additional charges might be associated with the '"free air". I don't know, but would sure read the fine print. Or, better yet, maybe someone with recent "free air" experience could share if there were any add-on charges.