I wish the answer you got was right, but you can get caught in a bind. It is quite possible to own land, sell it, and then reduce membership to basic - AND STILL PAY LAND USE FEES, even without permium membership. The system is broken.
To avoid this, after you get rid of land, but before reducing membership to basic, go to land management, and reduce your land holding fee tier to 0. Then change your membership to basic. I am still stuck, trying to get Linden to shut off my land use fees.