Doubt about Roy's death

Hi everyone, i'm a big big fan of Blade Runner, and maybe i've seen the movie ....dozens of times. But after all this time, the same question is in my head. The replicants have a security device, 4 years of life. Ok, if the movie is set on 2019, and Roy is created in 2016, why he dies one year before the end of his programmed life cycle???  maybe he commits suicide in some way??? Thanks for all.