Ehwhat? I swear that when your sub expired you used to be fine until you logged out, at which point you'd be unable to login again o-O
Or am I just showing my eve-age?
There are 2 situations afaik.
If you have a paid subscription with a credit card, and it fails, then you get the kick within a short period of time. You get a "subscription expired" message, and then in something like less than 30s, you will be logged out.
If you have a PLEX subscription, if it says it expires on say 10 june, then you can remain ingame until downtime appears, and won't get the boot.
Unless it changed (again)