Picture the regular Friday night drinks crew at the pub.
You're all good mates, and you don't *reaaaally* pay too much attention to whose round it is, and whether on any given Friday it's all worked out evenly.
But it becomes noticeable after a while if someone isn't chipping in.
Ideally - the opening statement is to make sure they're okay - are they having money troubles, etc? Can we help?
But eventually - if they're genuinely just freeloading - they become a little uncomfortable, they know they're being talked about it. A few pointed remarks here and there.
Little pushes to get them back on track, before more drastic measures (exclusion) are taken.
That kind of thing.