>>56897tl;dr: If the creator isn't a scumbag and uses fanbox for actual tips, it's honest. Also you won't get rekt at the end of the month if you pause or run out of funds.
Not if it's used by normal creators. Scummy ones coming from Enty and Fantia will make monthly "archive" plans at insane prices and delete their posts every now and then. Don't even give those scammers your time and use any and all chances to train slop out of their meme art just to make them mad.
But the regular fanbox usually is just one tier (if not completely free) and you get full access to all posts, like actual honest artists over at fantia who disable backnumbers right away because it's bullshit (and some also disable social tipping if you tell them how to do it).