I strongly suspect will forget what they gave you after a couple of
years, possibly less. And, unless it's something they made with their
own fair hands, they aren't likely to recognize it if they see it for
sale on eBay or Kijiji or craigslist or whatever. Especially if you use
a screen name and not your real name.
I mean, say I give you a copy of "Ken Butler: Does He Really Exist" for
Christmas then later see a copy for sale, how would I know it was yours?
Billions of people have the book, not just you.
Anne, one-finger typist on phone girl