Homecoming makes no effort to explain this interaction, but people on Reddit have their own ideas . Namely, since the concept of a "roller" was something they spoke about launching earlier in the meeting, then it seems to be what Audrey was using and the same medicine that was given to patients at the Homecoming facility. The project shut down, but it appears they didn't stop making the drug, and perhaps have perfected to the point that it can erase specific, recent memories. Of course, that brings us to the next question: Why would Audrey want to erase the memory of her firing Colin? Is it just because it gives her anxiety, or was she ordered to? After all, we don't know anything about this new position of hers.