I do believe it says you have to email them (bottom, under General, license) to get an offer but I see they have a freebie for indie comic makers so you can use the free ones anyhow you like. I dunno, I always preferred things clear-cut and a pro gave me this advice early on: Buy a thing, never have to worry about license changes. Just in case, ya know, you end up super-popular and selling a ton.