Please seriously consider *not* using ads to generate revenue. We need to return to other models rather than just slapping ads on everything. Be the change you want to see in the world. Do you really want to see more ads?
Have a look at https://examine.com as the closest site I can think of in this space, and check out their revenue models.
Without ads, you are just gatekeeping it from poor people. You can make the premium ad-free, but making the free version ad-free is basically asking for the price of the premium version to be raised to subsidize everyone else.
Have a look at https://examine.com as the closest site I can think of in this space, and check out their revenue models.