move on, deal with it, or go see your doctor about your cough which could be many other things than 6 month old, painted over nicotine remnants.  

I am going to have to pay for remediation in a month when he moves out and I'm concerned he will continue to deny in-unit smoking and fight me on security deposit deductions.I found a kit online that tests for nicotine residue.  

I baited all the traps with some “mouse food” gel.

Their lease is over the day they left,  you can charge them rent up to that day, on an eviction, not till the end of the month.2.Nicotine stained walls is something you can charge for, so I usually charged an extra $250.00 for just that.3. you need to send them a move out statement regarding their security deposit.. you charge for any rent owed, legal fees/court costs, and damages over and above normal wear and tears.

look at the walls or drapes in the rentals. smoking will eventually lead to nicotine stains on the either.

@Frank Szymanski I am currently in the process of staining my golden oak cabinets using a dark gel stain.

Have you tried Advion roach bait gel?

I've been to the meetups and I can definitely attest that it's a real life community of like-minded people who are go givers and all gel together well ! 

Now if only I could stop the "Gel Queen" from jamming the old bath tub P-trap with coagulated hair & gel it would be amazing accomplishment.

We raised their rent from $500 to $780 & they now pay for the bi-annual cleaning/servicing of the evap coil on the furnace because the smoke/nicotine residue is so heavy.