What is the ruling on selling strategic game resources collected within the game to strengthen the player, knowing that the game developer prohibits this?

It is permissible to exchange for in-game additions if the game is permissible and the additions are known. However, if the producing company prohibits this exchange, then this falls under the issue of the seller stipulating to the buyer that he may not dispose of the sold item, and scholars have differed on the obligation to fulfill this condition.