Keep in mind as a month to month tenant your also free to give your proper written notice on real paper sent via a method that gives you a receipt such as confirmed mail delivery to the LL telling the LL your going to move and be done .( keep a copy of the notice stapled to your postal receipt) since you don't have a written lease your LL can only change terms with proper notice and cant go retroactive so if your LL wanted additional rent from you having someone stay with you such as a GF then it had to be written into a lease or proper notice of the change made first.