I had the same thoughts when I was reading the reviews. Even if the reviews were honest, I'm not sure they would be as high if they actually had to pay for the product. The product is seriously expensive and has a really stringent EULA requirement. I'd really like to have read a review from someone who completed the entire program and had paid for the program itself.
I don't see why you wouldn't be able to. You might be able to create two separate profiles for them, but if not the only downside to that would be that while you can redo the exercises it would not say where each specific person was.