Never noticed the Join for free box - still don't see it. Regardless, I get what you mean. This is why I load very few apps on my phone - there is all kinds of jazzzzzz that comes with free or join for free conundrums!
I did notice this today which I find of interest on the SR front page - it's about peyote. I lived in SW for many years and ran across this cactus on more than on occasion. Peyote proved to not be free for me, but the informative article is!
All About Peyote