So....Tom and Harry signed a lease for an apartment with John Q. Landlord. The initial lease term was one year, and the lease contained a common provision that, upon expiration of the initial term, the tenancy would convert to a month-to-month tenancy on all the same terms. At some point (your post doesn't indicate if it's before or after the expiration of the initial one year term), Harry moves out. However, neither Tom nor Harry bothered to tell Landlord that Harry had moved out. And it is now some unstated number of years later. All correct?
No, it's not correct. In fact, it's absurd. Where did you come by this understanding? Harry is a party to the lease. That he moved out doesn't change that.
Not really sure what this question means.
Let me guess: You're Harry, and Landlord is coming after you for something, and you're trying to find a way to escape the consequences of your failure to notify Landlord that you moved. Right?

