This happened to me try and help someone out and all they do is cause more problems! In my case it was 2 months yes I had to serve him with a 3 days notice cause he stayed longer than a 14 day period! A 3 days Notice is to pay rent or quit(move out). My friend moved out. Good luck! If its a permanent roommate situation get a deposit next time then you know there're serious about their obligation!
If you put pressure on, you will get a promise to pay in 10 days, and then excuses near then about "unlucky" new bills etc etc etc.... Its a common tale, these sort of parasites are toxic to trustworthy people. Give them an hour to be out or you will call the landlord and start official processes. Don't take sob stories about where they stay that night. Don't let the arrears get even $1 bigger, you are never going to get it. Sorry, speaking from experience most adults have had.
Before you allow anyone to move in with you as a roommate , Write up a contract in full detail as to their responsibilities pertaining to rent , Utilities , Appearance care of the dwelling , Include every detail you can think of , After revising your contract , Final print it and at the end of the contract , Include , "Signature of Leese" . (Person moving in ) , "Signature of Lessor" . ( Person who leases or owns dwelling ) , "Signature of Witness" , Next is , Take it to a bank or notary public and have it notarized which upon signature , The contract becomes legal and binding , In the meantime , Gather up ALL documents that pertain to rent , Utilities , Etc , I hope you have records of the months he paid rent , Utilities and other expenses and months he did not pay , To have as proof so you can sue him to recover the losses incurred , Tell him NO MORE EXCUSES , YOU'RE EVICTED , Have the police present when he is getting his belongings out so none of yours go with him , Once he is out , Change the locks immediately , Better yet , Pick up new locks before you order him out , That way you can change the locks right there