Make certain posts expire after a certain date/time?

Hello, all. I am new to blogging, and run a small WordPress blog (see https://www.hirgny.com). Does anyone have a way to make certain posts date-limited? For example, if a blog entry announces a meeting taking place, I would prefer that announcement to disappear after the date of the meeting (or a few days afterwards). Is this considered counter to the principles of blogging? Or, can it be done. I was thinking of adding an expiration date/time field, but then how would I filter? Not sure I have access to the core code, since this is running on a shared hosting basis.