Its ok. There are a lot of scammers on Listia, and I was recently fooled by one with impeccable credentials. I pride myself on being a genuine seller, so everyone please take note of this and bid with assurances that what you will get is the genuine unused code.
Basically, you have to link a bank account to Listia to enable selling. Listia also wants people to link their social network to the site, as well as a phone number
Did some checking with my fans' accounts, and some of them still haven't synced their bank account, and yet have still managed to sell on Listia for quite a while. I guess if you're planning on only using free shipping, then you don't have to worry about it