I've been told that packaged photo chemistry has a definite shelf life.
In the past I had problems with this developer. I ordered several bottles from a well-known photo retailer in Melbourne, which came by post in a few days. Silly me, I didn't check the use by dates on the bottles. About a month later, I processed several films with a mix from one of the bottles. My films came out ruined, and on checking the bottles I realized they were long out of date.
Alas, the developer was well past its use by.
I now mix my own from basic chemicals. Mostly D76, an Agfa-Ansco ultra fine grain developer, and now and then a two bath from recipes by the late Barry Thornton. All of which serve me well. I no longer store the developers, once used they get recycled.
Indeed, stop bath can be mixed from household vinegar - you can check the internet for recipes for this.
As for fixer, I'm not so sure. A now-deceased friend mixed his own fixer from pure hypo and nothing else. He did this for many years, and seemingly had no issues with the longevity of his finished films. As he is now gone I can't check the current condition of his rolls.
As I tend to be quite cautious in my darkroom routines, I now buy mine (from a different retailer) in liquid fixer, and in quantities to ensure I will use it all up before it becomes 'vintaged'.
There are always risks with storing photo chemistry. It's wise to be cautious with liquid chemistry.
