This so much, people would abuse an exchange policy so much since it would require no effort to just press a button or send an email to request one (unlike the exchange policies for physical things where you would need to ship the product back or walk to the store yourself and personally explain why you no longer want the product.)
There's a reason exchange policies don't exist for most digital products. You don't see exchange policies for digital music either.
The risk that you may not like it is something you take everytime you pay for entertainment, whether it be a movie at the cinema, a book, a comic or a videogame. Refunds or exchanges in the case of entertainment and most consumables are something you can only demand if there is a huge gap between what a product claimed to be vs what it turned out to be (say the free episodes are all heavy detail full color, and then the paid ones are suddenly stick men shouting "No don't touch [Love interest], she is mine forever and ever!"), or if the product was just not properly delivered to you (for example you paid for an episode, unlocked it and got nothing or a broken episode).
