Come up with a more formal agreement.

She's **** right now and you'll almost certainly take advantage. But you're not an unfair man.
"We can come to an arrangement..." you trial and see her body already begin to relax slightly. "what you're asking is quite out my usual business" her body tenses once again "but I can do it if you continue to be able to make as compelling and persuasive case as you are now... Though I would need some more" you pause slightly and study her face to this. She doesn't react much beyond a slight nod. It is probably more recognising what you are saying. "would you be able to provide more persuasion. Regularly for the course of the loan" she tenses at the second part but the softens quickly again.
"ye-yes I'm sure I would" she fumbles at the start but grows into the confidence as she speaks. "perhaps I could make a persuasive case while you prepare the contract right now..." she says as her hands reach for your belt her finger tips brushing against the obvious bulge in your jeans.
"Yes I think that would be most helpful" you say as you smile. You can't help but respect her directness, and find the not quite eagerness but adjacent attractive.

You wake your computer while she undoes your belt with confidence. As soon as you've begun to draw up the contract document she has both hands around your shaft.
She's not hanging about as both hands expertly work your entire shafts with a passionate intensity. Her body is near yours and you feel her eyes flicking intensely both from your dick to your face. Your own eyes can't help but flick to the attractive woman working away at your dick with her hands.
You explain the general terms of the contract and she pays close attention but does not miss a beat with her hands as they glide up and down your shafts.
When you get to the money she spits on your dick and begins to ensure her hands cover you in her spit. She does this again a few moments later when you note that the 'assessments of the clients suitability for the loan' will cease upon final payment.

Your body is already beginning to tense as you near completion from her expert hands. You inform her you have signed it and that you will print it for her signature. You almost expect her to spit once again but as soon as the printer begins to whir into action in the corner of the office her head lowers to your dick.
You feel her tongue part out to flick delicately across your tip, tasting your precum. Before her thick lips part around the tip of your dick taking you into her warm and wet mouth.

You know quickly that you won't last much longer as she begins to slid her whole mouth around your cock. Her head bobbing up and down around the majority of your shafts, whilst her right hand strokes the base with equal enthusiasm. Her other hand rests on your thigh her finger tips brushing against you slightly even as she focuses her efforts.
For the most part, and it's not like you're lasting long against her, she is focused on her task but occasionally her beautiful brown eyes glance up at you. When she does this once more you can't help but be pushed over the edge as you soak in the beautiful sight beneath you.
You mutter as such to her but she is not surprised and not falter. If anything she increases her vigour with her mouth moving to focus on the tip and both hands working together on your shaft now.
It takes only a few moments more before you are releasing into her mouth. Your hand goes to her shoulder as you do, both to steady yourself but to slow her slightly as the intensity threatens to be too much. She does not pause and you watch as her brown eyes look up to yours as she swallow your cum. She pulls back after you've completely finished. Giving your now much more relaxed dick a quick peck before releasing it with a slight wry smile on her lips.

You need a few moments to recuperate but before long you are both standing dressed once more and she has signed the contract you had printed.
"Thank you" you offer
"No thank YOU" she offers back seemingly genuinely. She is smiling just slightly.
"The funds will be with you by the end of the week" you say and she nods and thanks you again. As she begins to walk out you can't help but admire her ass in her black dress. But you also notice the relaxed spring in her step.