I purchased my (what I figured would be) final copy of the original Final Fantasy 7 on 6/16/2013 (June 16th). Prior to that, I bought the PSX version 4 times, and besides disk 2 on all but one copy, I have 2 fully working copies for that platform. I don't own a PSX anymore, nor do I actually know where those disks are.

The Square Enix site shows that I have that copy, but I can't get the serial number? When attempting to log into the Square Enix store, it gives me this error:

"The login details you have entered are invalid, please try again.
If you are trying to login to with your account from our old store, please create a new account. For more information click here."

If memory serves me, that's the only way to get the key, but obviously I bought this game long before the store got overhauled. So where is my game?

To be clear: I have the download from April 2nd of this year, but can't get it to activate without my serial key, which seems to have disappeared from my email (I'm very careful with my electronic invoices, and have no idea what happened).

How do I get my key?