Your Hackerspace might be so cool that people will want to pay you to use or access the space. Just make sure they don't destroy it!
If you decide to generate income by renting space or time, have a contract detailing who the responsible parties are and what they're responsible for. Make sure your contract or written agreement has concrete cleanup terms, ways that your space can and can't used, what will be available and not available for use, and anything else that may come up after a rental. This way if there’s a discrepancy or issue that comes up later, both parties can review the contract to see what was agreed to. Have everything in writing in email or otherwise. A paper trail makes it easier to resolve disputes and gives you a template for doing space rentals (and events) in the future. For sample contracts you can use as a template, and make your changes accordingly.
Don't forget to check in with your membership about the dates, or refer to your calendar system.