Game mode: [Online | ]
Problem: [Bug]
Region: [Asian]
i put a Potion of Bestial Memory in one of my chests and it disappeared. Today i killed an monster and got Two Potion of Bestial Memory, as soon as i closed my inventory and opened it again, both were gone.
Later i made Two Potion of Midnight and both DISAPPEARED!
Both these things sounds as intended gameplay. Food is consumed immediately since 1.40 patch for pets and thralls. Some foods give a buff to the pet or thrall.
Potion of beastial memory has a time of 2 minutes then it disappears. You can store them in the preservation box.
There are some inconsistencies in your report. You mention storing them a chest and then them disappearing from inventory. As others pointed out their decay timer will start running as soon as you loot them or craft them. From that point onwards you have a very short time to consume them or store them in a preservation box with some ice else you lose them.
You dont specify if you play on official or not but if on top of that the spoil rate sliders have been modified, it might be why they decayed so quickly.