Tips for protecting myself on digital code sales

I have over 700 sales on Gameflip for rocket league in game items and use a pretty fool proof process for protecting myself against scammers but I have a digital code ha I would like to sell and am not sure about the process of protecting myself in that instance. My concerns…

  1. If I choose to sell a code as instant delivery then from what i understand the code is delivered as soon as the transaction is paid for but what is to stop the buyer from redeeming it and simply saying that the code didn’t work. It’s not like an in game digital item where I know that they receive an item (because i personally deliver it) and I take video proof of the whole transaction. With a digital code her is a grey area because I am not there to see them redeem it and collect video of the redemption. In that instance what proof would he have to provide in a dispute and how do i protect myself from being scammed?

  2. As i understand it there is an option to also sell using the deliver manually within 3 days option. I like this idea better because then i can at least view the buyers feedback before I send and possibly cancel the sale if I am not comfortable with his feedback however my concerns from point 1 still apply here. Any opinions on this method of sale?

Any information on how to protect myself in this case would be appreciated.