By law does the landlord have the right to accumulate late rent fees over the past few years and request it in full at the end of tenancy? They did not provide any notice to tenant and have been continuily accepting the monthly rent payments and have not requested late rent fees throughout in las vegas, Nevada

When your sign your lease, at least up here in my province/city, there is a notice in there about what the charges are for late rent. I think it would be up to the landlord to make sure that the right amount of rent is collected. If there isn't any mention about any fees for late rent then no they can't. How much are we talking about here?

There is no Nevada law about late fees so carefully read your lease. If late fees are prescribed the LL can collect them even if he waits and wants a lump sum. The LL cab request, the tenant can pay or not pay. It would then be up to the LL if he wanted to sue. He can not keep the security deposit for late fees unless that is also in the lease