all you need to do is buy a package or orange silica gel beads that comes in a sealed package, like ziploc or whatever. i use this but its far more than you need for a pair of iems, really.
https://www.amazon.com/gp/product/B01I5Y9H6A/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
get a jar, pantyhose, and another ziploc bag. cut the foot end off a pantyhose and throw half a handful of beads in it, and tie it. so now you have a bunch of beads in your little tied end of pantyhose sac. and after this, every so often put your iems in the jar with the pantyhose sac and seal it for a night. when you take the iems out of the jar, put the pantyhose sac in the other ziploc and store there until next use, and it will stay almost completely fresh for many uses. after several months youll need to replace the beads. now you have a setup that will last you for years with no maintanence, and no buying. I live in a place that gets ridiculously humid in the summer, and take care of ancient coins, meteorites, and iems like this, more or less. it works and theres no fuss no muss. and no heat.