I believe it's generally understood that using steroid hormone medication does in fact lead, in time, to your body lowering or stopping its production of those hormones. I have no citations or references to share. Please do validate the information on your own.
I think even short term use can cause underproduction, and require tapering off the drug to allow the body to come back up to speed.
This last bit I'm really not sure of, so be suspicious: Long term use, I have a vague sense, may result in complete stoppage of production.
You might try licorice to boost your cortisol levels. Licorice works by slowing the breakdown of cortisol. So your glands don't have to work as hard to produce as much as you need. But your glands are still the things responsible for producing what's needed, so they should still continue to produce. Again, I don't know these things for sure.
I bet that you don't want to quit licorice cold turkey either. I've been using it regularly for three months now to seemingly good effect, but I want to make sure I'm not overly coddling my glands/system, so I'm going to stop taking it. But, as with steroid drugs, it probably makes sense to taper off. So I'm going to try that.