Mr. Jeffries is correct. It is likely that you living there has made you a tenant and should be evicted as such.

They are allowed to charge what was agreed on in the lease. If you leave a lease early it is breaking the lease and will likely have a penalty.

Try talking with the landlord to see what happened and resolve it.

This is something to negotiate. They are asking you to leave before the lease ends... this is worth something.

You could sue the roomate to recover the money, but odds are they wont pay.

Whatever the terms of the old lease that carried to a monthly rental would control. Those terms coukd not change except at a lease break and with...

Sounds like they allowed him to reside there under the lease (not as a perk of employment) likely waiving their right to object.

Sounds like he would have a good arguement for monthly.

Mr. Kaufman is absolutely correct. The landlord should maintain a key for use in times of need, so you shouldnt have to leave it unlocked.

Although you could likely take some action, it would not be worth it.