also explains what makes a person the same person over time:

consciousness always accompanies thinking, and 'tis that, that makes every one to be, what he calls self … in this alone consists personal Identity, i.e. the sameness of rational Being: And as far as this consciousness can be extended backwards to any past Action or Thought, so far reaches the Identity of that Person; it is the same self now it was then; and 'tis by the same self with this present one that now reflects on it, that that Action was done.

The diachronic (over time) sameness of a person's identity consists in the sameness of consciousness over time. In other words, in memory. Thus, in instances of forgetfulness or memory loss, there can be a change in person (identity), even if there is no change in the soul.

Thus, when Jennings signs a contract to lose his memory, he literally signs over his personhood by agreeing to have his memory erased as the equivalent of a nondisclosure agreement. As present-day Jennings discovers, during the two years, he worked on a secret machine that allows people to see the future, and the bag of trinkets is a curated collection of items to help him survive. When he realizes the extent of the work that his past self did with Rethrick, he begins referring to that self in the third person. Critic Zack Handlen wrote,

This is still early Dick, which means that ... there's some play with identity- Jennings develops an overwhelming faith in the prescience of his past self, a faith which most people can’t ever have in their present versions, and by the end he's even referring to that past guy as a separate person.

Not only did the past self of Jennings work on a project to build the illegal machine, the present-day Jennings realizes that Rethrick is secretly building a revolution to overthrow the authoritarian government and eventually joins them as a partner. By having Jennings refer to himself in the third person, the author is making a comment about the trust that Jennings must have in his past self, even though he doesn't remember why the past Jennings decided to forego payment in the favor of seemingly worthless trinkets.

As the post-WWII arms and technology race between the US and the USSR accelerated, so did skepticism and concern about both the overreaching behavior both of large and powerful corporations and the federal government. When this novella was published in 1953, Senator Joseph McCarthy was using the authority of congress to seek out and destroy so-called ideological enemies of the country from important positions. Even in this early example, we see one of Dick's trademark effects in the sense of paranoia and confusion regarding time and identity stemming from the shadowy machinations of large corporations and secret government offices accountable no to one.

With this context, we can understand Dick's motivation in Paycheck to explore a new kind of power dynamic between the individual and the powerful interests pulling the strings in secrecy and opacity. Imagine a future when in return for a generous salary package to do a possible unethical, illegal, or otherwise unspeakable job, the candidate must give up their right to two years of their conscious life and memory. For Jennings, this must have seemed like a good deal before he needed to face the consequences of his lapsed memory and its fracturing of his true self. This is why Jennings uses what he calls "the objective" pronoun when referring to his previous self whose memory was erased. Although Kelly isn't sure at first whom he's talking about, Jennings assures her "It's easier" for him to think about that previous person as an "object", like an unwitting pawn in The Company's game.