You cannot just move a Seminar Room to the ‘Meetings’ tab in the usual manner
Not renewing the Seminar License should not actually remove the content at all. The rooms will still be there and the recordings and content will still be there, you just cannot run a meeting there.
That said, I personally move the recordings out of the Seminar Room area to a folder in the ‘Content’ tab just to be sure. Just a regular move as you would normally (see this post)
Another trick to be aware of is that you can use an API call to move the actual Seminar Room from the Seminar License area if you want to have access to it in the future. Note that this is a suggestion from a third party so be conscious that this is not something we can support in detail, but these guys are incredibly sharp and this might be useful in a pinch. Your technical guys can tell you if this works for you before you try it.