There are no requirements or restrictions preventing you from publishing your content on any other platforms! The content you make in your Meetn room is 100% yours.
After your event, all you need to do is retrieve your recording from the Menu > Events & Recordings > Event Name > Manage Replays & Recordings. Download your video file and then you'll be able to upload it to your channels on any other platforms!
After you download it from Meetn, you may keep it stored in Meetn's cloud or you can delete the event to clear up your cloud storage. Either one is fine, it's completely up to you!