I suggest having property reset on players that aren't active on the server which like didn't come online for months. Because lot of properties I've seen are owned by someone who didn't come online anymore.
I've experience this kind of script before back in other server. It's like when you approaching to the property's red marker, you can see last online for owner of the property, and players can ask admin to reset it as if the owner didn't come online for 6 months or something. Though this is just a little suggestion from me, because this script might be not demanded that much, but I do think some of the players wanted to buy property but most of them got occupied by some inactive players.