We’d like to share with you how Search works and why the limitation is set on 30 days.
Basically the reason why we have to limit to 30 days for categories is because searching across a large number of feeds takes a long time to return results right now. This also explains why we can remove this limit when you search directly in a feed rather than a category, as that will return search results a lot faster.
You can still see all the older articles as unread in all your Collections/Categories. If you’ll click on the Gear icon on the top right and uncheck “Unread only” you’ll see all the articles, just marked as read.
Improving our search feature is one of our top priorities for feedly Pro, so we’re trying to up this limit soon. Unfortunately we don’t have an ETA to give you on that.Joni commented
Newsblur has this feature - unlimited feeds! I just converted to their premium users, costs a couple of bucks per month. Since Feedly is not taking this seriously (no response here or anywhere else), and Newsblur has an unlimited history (and they seem to be nice guys too), it seems like an obvious choice.