Think about it. - unless the designer/ manufacturer was going to patrol every craft fair, yard salem, rummage sale, auction, Etsy site, eBay site, individual web site, private purchse, etc. - how in the world would they even know you made something out of their fabric then ( gasp) SOLD it. Totally unenforceable statement. As an individual crafter don't lose sleep over it.
Now they do go after the big ones (Chinese knockoffs, etc.). but are not real successful even then.