Would you look at that! You’ve cleared all the sectors of the laboratory at least once and got out there alive. Congratulations! Now, from this very moment, in one of the terminals near the reactor, you’re free to install new perks and (anti-)threats. You receive both as a reward for increasing the reputation of the laboratory, that is, for clearing it in hardcore mode. As for the new perks, everything should be simple. The activated buff will be added to the list of all other buffs that will be randomly offered to you upon entering the sectors. But what are those anti-threats? The anti-threat activated in the terminal guarantees that a threat with such a description will certainly not be offered to you during the subsequent clearage of the sectors.
Finally, you activated a perk or anti-threat (the number of slots for them both can be increased by improving the bioreactor), used the elevator, found yourself in front of the entrance to A1, opened the sector... Now you’ll just have to deal with the consequences of that choice. You will not be redistribute perks and anti-threats (if you have a lot of them), until the laboratory is renewed.