Most selected sites will have their cookies cleared (not all though).
You should uncheck the sites (or add to excluded sites) for which you have an account or else you will be logged out at every visit.
If you want to also block general paywall-scripts for non-listed sites you have to opt-in to custom sites (permission for access to all sites is needed).
To view some sites (check list) a necessary cookie has to be set (enable this in opt-in).