Some other member posted about it on the main thread that Decryption Keys are limited to 9 at a time.
Yeah, my goal was to lock them at 9, but like I mentioned before when I tried to narrow down their address in CoSMOS I was left with 8 or 9 different memory addresses for the Decryption Keys. I tried locking them all at 9 and was able to keep them that way in the shop screen, but once I did that and left the shop screen the game crashed and when I loaded it back up and tried again the memory addresses I had saved for the keys were not longer matching. This led me to assume that the memory addresses for inventory items change every time the game is loaded. I have limited experience with CoSMOS and CE so I am not sure if there is a way to compensate for something like that or not.