A lot of you probably bought a GTX 1070/1080 during the eBay sale or from PC Byte and don't know about this. Promo started on the 22nd so your receipt probably needs to be dated after that date. Link is to the Gigabyte one since that was the most popular.
Gigabyte: https://xg.gigabyte.com/event-detail.php?i=103
MSI: http://event.msi.com/vga/2016/nv_q4_watch_dogs2/
Asus: https://www.asus.com/event/VGA/watch-dogs-2/
Bah… bought my ROG Strix on the 17th… :(