This story came up on another site. Lease says tenant pays 1/3 of the utility bill. Landlord maybe bills once but never collects, then 10 years after the lease has gone MtM presents them with a $7000 bill. Sounds to me like he's got no chance, there's got to be some precedent set by never billing and collecting, right? I've never heard of such an open ended liability.

He can bill , but will he collect ?   I am pretty sure there is a statute of limitations  

Commercial or residential property? Factors include the wording of the original agreement, when the original debt was due, how it was billed, and if the tenant ignored the bills and let them accrue. There is probably more to the story. Perhaps the landlord sent a demand letter for $7000 regarding past debt that had been billed and never paid. But unless the landlord kept up on it, collecting an old debt is probably futile. Even collection agencies can't go after old debt if it has been ignored too long.  I seem to recall collection on past debt must be initiated within 3 years.

Statue of limitations and waiver issue so if the LL can collect it will limited to a set time. By not attempting to collect over that time a court could rule the LL waived the utilities provision because they never attempted to collect.

Nobody can answer this question without the jurisdiction, the actual agreement and the facts surrounding the dispute. Yes, there could be a limitations issue but some jurisdictions permit a significantly longer period to sue on an account.

I suspect he'd be wasting his time. I hope the tenant is gone.