Inevitably, this moment will come for every long-term host. Your guests loved your space so much (or it's just so cold outside), that they're not really making any movement towards the door. You were understanding for the first 30 minutes, but after the first hour frustration starts to build.
This is one of those moments that are truthfully better to curb before they even begin. If guests are staying in your home, ask them the evening before what time they plan to leave, and if it's later in the day, remind them that check-out time is 11am. Let them know the cleaners are arriving shortly after, or simply that you need to prepare the room for the next guests. If the guests are staying over while you're away, send a message at 9am that same morning. It should always be friendly, and always assuming the best. Let them know check-out is 11am and ask whether they need luggage storage or a car service (if applicable).
At first, it can feel rude or awkward telling a guest they need to leave, but it shouldn't! You are, after all, running a small-scale bed and breakfast, and they are not relatives visiting for the holidays. Keep the conversation light and simple, and it won't be a big deal. If your guests ask to stay longer, don't feel obligated to let them unless it is truly no trouble at all for you.
At the end of the day, you want to continue to enjoy hosting. You and your guests alike will all be happier for it!