Where you buy the horny spray, you need to scroll all the way down, and there will be "Horny Boosters" you need to buy one, to get +1 horny bar of monster
Thats the trader's market. You can buy the empty lube bottle, and then fill it up in some weird machine, then get this bottle to the trader, and she will give you some "cumpoints". Cumpoints can be used to unlock the scenes you already did with the monsters for permanent access on pornhub site.
(Also, you can use horny spray on trader when she's peeking to get your bottle.)