Ok now that im more awake, I dont see a legal obligation to keep replacing the lock and the LL being obligated to be the one to do the break in but the deal is this, if the tenant began to leave the unit unlocked the risk to the LL becomes that anyone who decides to rip off the tenant may spread the word of a unlocked unit and do a forced take over to cook & sell drugs, turn tricks, plain old trash the rental then the LL is out even more in damages so the best bet may be button pad lock where the LL will still issue a key to the tenant but should the tenant lose it the lock could be programed to tenant year of birth , tenants moms last four of phone, any number of things that the tenant should remember so if the tenant called up` hey mishterr lanlord while I wash owwt I losht my key` LL can remind him` push in 4978 your birthday and it will open` still a hassle for the LL but no need to show up, no changing the lock again, lower risk of say windows being used by tenant to climb in, reduced risk of tenant choosing to just leave it unlocked, etc and yes the LL can make the tenant pay for this if the lock has already been changed and tenant loses key again. ( and yes at some point LL should decide if they really want to continue to rent to this tenant)