Here’s what consumers have asked with answers from FreeShipping staff and previous consumers.
You can get a "free" trial (usually 7 days) but after the trial, it is a paid service. The charge is $12.97 per month ($155.64 per year).
You did sign up for it. At some point during a regular online purchase you were offered 10% cash back. You accepted that offer and that's when you signed up for it. To cancel, go to FreeShipping.com and contact customer support. Also, check your email account for FreeShipping.com emails. That will tell you when you signed up.
Absolutely it's legit. It does have to be an order from one of the 1000+ companies that agreed to partner with FreeShipping.com. If you go to the store via the link at FreeShipping.com on their page for that store, then, after you place your order, you can request a rebate (of up to $10 max per order) to refund the shipping you paid. So, no, you can't buy from a private party and still receive a rebate for your shipping cost.
I'm having the same issue. That's what I've been charged. I've notified my bank to refuse to honor any more of these charges. I contacted FreeShipping and all they responded with was "we see you've cancelled your membership." They have not answered my question as to what it is for which they've been charging me.