I use the free version and for my needs it's fine (basically 100 feed limit and after a while old posts drop off the feed, I'm not sure how long). For 25 dolla

I use the free version and for my needs it's fine (basically 100 feed limit and after a while old posts drop off the feed, I'm not sure how long). For 25 dollars a year you get 500 feeds and one year retention (up to 1000 posts per feed) and you can pay more for a larger number of feeds.