In the Ridley Scott 1982 film "Blade Runner", all the Nexus 6 replicants have a lifespan of how many years?

In the 1982 film "Blade Runner", all replicants are built with a limited lifespan; the Nexus 6 are genetically designed to have a very short lifespan. Each model has only a limited four year span. In the film Roy Batty, perhaps the most perfect of the Nexus 6 series, and some of the other replicants return to Earth. They are seeking answers to questions about their lives. But Tyrell tells them that he is unable to alter their genetic make-up and specific 4 year lifespan. Is he lying?

The Nexus 6 series of replicants (genetically engineered by the Tyrell Corporation) are virtually identical to adult human beings. Plus they have superior strength, agility, a wider pain threshold, and variable intelligence depending on the specific model. So Earth law now forbids replicants on the planet, except in the huge industrial complex where they are created. The law does not in any way consider replicants human and therefore accords them no rights or legal protections. They are on their own for the four years that they may live.

The clever Nexus 6 variety, which is not reliably detected through the complicated eye scans used on previous models of androids, are especially feared. And, they are hunted and assassinated on Earth. Will any human now question what their own identity or role should be in the future? The replicants have said, "They want more life..." The Tyrell Corporation has advertised this model to be “More human than human.”