Hi Penny, welcome to ECF, and congrats on such a good start to your journey to being a non-smoker!
Coils' life time... lot of variables, it's hard to give a definitive answer. Thick, dark, sweet flavors tend to gunk coils faster than thin, light ones. Vaping power can affect it...
I mostly use bottom coil clearos, but life is similar. I try to clean them after every couple of fills, taking them all the way apart and rinsing it all under hot running water. I'll dry burn if needed. With bottom coils, I generally replace the flavor wicks, and just use 100 % cotton yarn for that. (Top coils don't have flavor wicks.) Kept clean, maybe a month or two? Hard to say, as I have several in use at any given time, but they can last quite a while.
The biggest problem is when the coil gunks up from normal carmelization, and a good dry burn will take care of that. Over-zealous dry-burning can "pop" and destroy the coil, though!