activating the retail version of Spore (from 2008) on orgin

I bought a copy of Spore years ago for my desktop. and now I want to put it on my ultrabook (which doesnt have a CD drive...) but i keep getting an error on origin saying "the code's already been used" ...I hear that you can still connect the retail version through Origin so i can download it on my ultrabook and and play it. I was trying to figure out how I can do this.