According to Nate over at the digital reader, it appears that you can only have your computer registered to Entitle’s ebookstore or to another ebookstore, but not both.
http://the-digital-reader.com/2014/0.../#.U5OTtuBye9M
So if I use this, I can't buy any other books from other publishers who use drm. Who's bright idea was it at Entitle to not allow me to use my own Adobe ID? Just another example of how well drm doesn't work.