system
A chat on subreddit /r/wallstreetbets
human
Futures are fixed delivery and without canceling. 
  
 The problem for the gas station is they are offering any time redemption. Thus buyers will only ever opt to use their optioned gas when the spot rate is high. If these were futures with a fixed buy date then the deal would be a bit less a loss leader for the gas station.

gpt
This is non-fixed delivery without cancelling, all you have to do is build in non-normal storage cost and it's essentially a forward... which is essentially an OTC future. 
  
 This is much more of a future than an option