Despite this deal being on for a while now, I have not seen it on here so decided to post as some may still be interested!
Simply go on the link and follow the instructions to get your first box free and then you can cancel your subscription before they charge you for another one.
Personally, I've had a few boxes from them and can say that they offer a good range of snacks that can be tailored to ones liking.
The deal is supposed to be for Vodafone customers, however, the link is universal and works for everyone.
(P.S. if you want another box you can use a different card with the same address )