Ads in between pages?

Is it against the terms and conditions to add advertisements to my comic like how the old newsstand comics would?
Would it be possible to have a feature like that where I can insert an ad page in my comic so that I don't have to solely rely on donations/purchases? Maybe it could be an option, for example, purchase an ad-free copy or subscription that removes all ads from my publications.
It's just another way of increasing revenue whilst incentivising the purchase of copies without putting content behind a paywall.