Paddle and FastSpring (I found their support to be more helpful than Paddle's but they charge even higher fees), the two solutions commonly used in that space, act as Merchants of Record. Since you are not selling directly to your users you don't have to file the corresponding taxes, just the ones that correspond to the transactions between Paddle/FastSpring and you. But I'm not an accountant and they may change their operations in the future so don't rely on this comment alone.