So I had problems where everytime I exited MobaXterm my key would disappear. After some browsing around I found a file that said this:
WARNING: You should not store anything in MobaXterm HOME directoy (/home/mobaxterm): with your current settings, this folder is not "persistant", so it will be cleared at each MobaXterm restart. If you want to set a "persistant" HOME directory which will not be cleared at each MobaXterm startup, go to MobaXterm settings window and choose a folder in which to store MobaXterm home files.
If you see this issue, try this to solve it.