What is the billing period for the utilities? If it's within your "last month" you might be on the hook for the bill. However IANAL, so might be best for you to wait to see if any legal action is actually taken. If so, contact a lawyer.

> The landlord I found out did not have a rental license the entire time.

&

>My landlord is threatening legal action.

LOL

What's the saying? Do one illegal thing at a time? If you're going to rent out a spot without a license, be the best landlord a tenant can have.

Assuming you're in the city, my understanding is: it was illegal for your landlord to collect rent from you and you are legally entitled to get all eight years of rent back. Get a calculator and decide if it's worth finding a lawyer to sue them (hint: probably yes).