Storing wax and fragrance
Updated
Two materials with completely different storage clocks, and usually kept in the same room.
Wax keeps, fragrance does not
Wax is effectively stable for years at room temperature in a sealed bag. It is not the problem.
Fragrance oil oxidizes, loses top notes and can discolor. It is the expensive material and the perishable one.
Storing wax
Sealed, off the floor, out of sunlight, away from anything with a smell.
That last one is the real risk: wax picks up ambient odor, and a bag stored beside open fragrance absorbs it. A batch that smells faintly of last month's scent is usually a storage fault, not a cleaning one.
Keep it below its melt point, which rules out a hot garage in summer. Partially melted and resolidified wax can behave differently.
Storing fragrance oil
Cool, dark, tightly closed, in the container it came in. Amber glass or the supplier's HDPE, not decanted into something convenient.
Fill level matters: a half-empty bottle has a large headspace of air, and that is where oxidation happens. Decant into a smaller bottle rather than leaving one part full for a year.
Most suppliers give a year or so. Treat that as real, and buy sizes you will use rather than the size with the best unit price.
Lot numbers
Write supplier, lot and date received on the container the day it arrives.
This is the backwards half of traceability and it is the half that answers "why did this batch burn differently". Natural waxes vary between lots and fragrance houses reformulate, and neither arrives with an announcement.