My mom just told me that she felt very comfortable after used ESTEE LAUDER Perfectionist CP+ on her skin. So as a good son, I am going to buy her some bottles of this product. But I am a guy who doesn't really understand the skin product. On the bottle is says 1.7 fl oz, I know 1.7 fl oz perfume could last for a while, how about skin product? How many bottles(1.7 fl)are enough for a whole year's normal daily use? Thanks ladys!