You remember

Catrya pulls her cockhead out of your mouth as you are coming down from your climax. Your chest heaves as you take several deep breaths, though because your mouth is so full they have to be slow breaths through your nostrils. You lean back, tilting your head up and instinctively preparing to swallow everything coating your mouth.

Before you can, though, your hazy vision is brought in to focus as Catrya dangles something just inches from your face. After blinking several times you finally see that it is an empty flask. Unable to ask her what she wants you to do, you glance up at the succubus and hold still, waiting for her to ready the next step. She rotates the flask so that the neck faces you and instructs, "In here. Get it all out."

You carefully part your lips just enough to kiss the small opening, trying to make a seal preventing anything from dripping to the floor and going to waste. You then tip the flask down, letting Catrya's entire load drip into it. Most of it flows down in several thick globs, each making a distinct plop as it hits the bottom of the flask. You then spend the next minute or so swirling your tongue around your entire mouth, making sure you get every single drop hiding in every crevice of your mouth.

When you are satisfied that you have deposited everything into the flask, you lift your mouth off of the neck and let out a very satisfied "Aaaaaahhhh..." Your chest heaves as you take another deep breath, finally fully recovering from your orgasm.

As you get back up to your feet, Catrya hands the flask to the shopkeeper, who is already waiting next to her with a rubber stopper. "Be careful with that stuff," she warns him. "Just having it touch the skin could drive a man wild with lust."

The shopkeeper holds the flask in both hands, unsure how to respond to that warning. After stammering some sort of undecipherable response he gently rests it on his desk, hemmed in by two piles of paperwork. He then picks up the flask holding the brimstone potion and carries it over to the two of you. "Thank you for your business," he mutters, barely able to look the naked succubus in the eye.

Once Catrya takes it, she turns to you with a gleam in her eye. "Let's go," she exclaims as she heads towards the door.