Google posts are a way of making your Google business listing stand out from your competitors and drive customers to your business. If you have something going on in the pub, you can post it with your listing so people can see something before going onto your website. You can add an event, offer or special information to your post.
Whilst you may not see the value of posts which disappear after 24 hours, Stories are a great way to show customers things that are going on in the pub that day. They also appear next to your profile picture at the top of a user's feed, which means they are more likely to reach your customers.