The meeting accepted the document.
If you are not registered, your article will not be published, which is equivalent to not being officially published. The copyright is still in your hand, and you can vote anywhere you want. If you attend the large-scale conference that you say you don't search, as long as the article is officially published, once it is published, your article can't be placed elsewhere. If this conference is just a simple exchange and no articles are published, your articles can still be put elsewhere.