Nice you are lucky i think. I got key from amazon and it doesn't work. I talk on support with nvidia and they told me key should be 24 digits while they send me a wrong one. I msg amazon back they still reply the same key over and over. I'm waiting from ASUS to see what they will say... This is really sad...
Enjoy your game ^^
I got mine directly from ASUS. I don't think Amazon will be providing it to you. (I am in Australia and followed the regional event T&C - Do check what your regional T&Cs are). Wish you all the best!