The listing, Dissidia Final Fantasy NT [closed beta key]PS4 -NA and LATAM regions has ended.
https://eu.square-enix.com/en/games/dissidia-final-fantasy-nt
The keys are for the Sony America store only - so for NA and LATAM regions - and you won't need to have a PS Plus membership to play.
How to redeem your code
Register for a free account at Square Enix
Enter your 6 letters + 3 digit + 6 letters + 3 digits code on the 'Redeem your code page'
Hit 'check code'
Click 'register product'
Accept the Closed Beta tester agreement
A final page will show your status as pending in preparation for the distribution of the PSN keys later this year
Keep an eye on your email for the closed beta dates and your key
The closed beta will be available to download between Friday August 25th, 2017 PDT and Friday September 1st, 2017 PDT. The closed beta will available to play between Friday August 25th, 2017 9 PM PDT and ending on Sunday September 3rd, 2017 9 PM PDT.