Answer: Lo Lishma, means that a person is seeking the truth. He has heard and theoretically has an idea what it is, but at the same time he still is in the intention to receive for himself.
If we measure Lo Lishma according to a scale from 0% to 100%, then in the case where a friend borrows $1,000 from me, 0% of Lo Lishma is when the friend must return all $1,000 to me.
1% of Lo Lishma is when he returns $999 to me, and I accept this as if he returned all of the $1000. And 100% of Lo Lishma is when he returns 0 dollars to me, an empty envelope. And I check this with my senses, see that there is nothing there and accept this as if he returned the entire debt to me. This is to say, this shows me how much I can go beyond the receiving desires.
But certainly all of this advancement is possible only due to the influence of the Surrounding Light (Ohr Makif). But when we pass from Lo Lishma to Lishma, then we begin to operate the Direct Light (Ohr Yashar).
Baal HaSulam provides a definition of Lo Lishma in The Introduction to The Study of the Ten Sefirot: “Indeed, practicing Torah and Mitzvot in Lo Lishma means that one believes in the Creator, in the Torah, and in reward and punishment. And he engages in the Torah because the Creator commanded the engagement, but he associates his own pleasure with bringing contentment to his Maker.”
From the 1st part of the Daily Kabbalah Lesson 11/15/13, Shamati #64 “From Lo Lishma to Lishma“