Removing People From A Room: Can they get back in?

I have allowed people into my room. My privacy settings, meanwhile, are that you have to be approved to enter.

So, when I approve them to enter, if they are not active when I allow them in or not heeding the instructions I’ve posted, I am removing them, just to be safe (for now). My event is not currently taking place, so that’s why I’m more likely to remove them at the moment, if I cannot get their attention when in the room. Ie, to avoid someone who might want to hack the room, etc.

I am not banning them. Just removing them for now. I would like them to be able to get back in later, with approval. I assume they can do that, as long as I’ve not banned them. Do I understand this process correctly?

Specifically: Can my guests whom I’ve allowed in, but have now removed, get back into the room? And, if so, will I have to approve them each time? Or, if I approve them once, does that allow them in w/out approval the next time?

Thank you!