I just fixed mine by searching through my email - mainly my spam folder - for this new email that came out. It was definitely there, but that doesn't mean this isn't a complete and utter cluster f*ck. This is 3 different keys I've had to screw with since purchase. The product key that I had to convert into an early access key and now a NEW key that I need to enter again? What's the point? If we had early access then we clearly made a purchase...

I digress, look hard for an additional key in your email. As previously stated, if you bought it through the FFXIV site it is going to be from webhelp.v4 or something akin to that. Otherwise it's likely going to be an email from the retailer from which you made your purchase.