European use by symbols

I'm spinning this off from my current post on discontinued products. I just became sentient of the open lid container use by date on European soaps. My Dusy has 9 M, Pre de Provence 12M and Mitchell's Wool fat 36M. Does this refer to a use by date once opened, exposed to water, five minutes after the shipping van pulls away from the loading dock?
I'm NOT panicking. Am I?

Good question. I *think* it is supposed to mean that it expires X months after the first use. But it seems that depends on the product and the ingredients (ie preservatives). Soft soaps and creams seem to expire sooner than triple milled hard soaps.
That said, my Tabac soap is marked as 36M but I used it for the first time 4+ years ago seems to be like new in its porcelain container.
Pannacrema Vetiver (old formula) is marked 24M and it has started to dehydrate/shrink after approx 1,5 years of use.
Proraso Green is marked as 12M but it is like new after 1,5+ years of use.
A Kent soap that I have been using for more than a year now is in relatively good condition, with small cracks only. A little dehydrated. Before that I had a MWF (I know, it is supposed to be the same soap) and it had major cracks after ~8 months of use. I threw that away. I have a Kent and a MWF soap unused in their original packaging. I hope they will last for years!

Ask churchilllafemme. He regularly uses soaps that are up to 100 years old. I think the only issue with some of those is that they are completely devoid of any scent. So I think you'll be alright.

Creams have a shorter shelf life and perhaps can go bad, but I never pay any attention to the dates on soaps, especially the triple-milled classics. The soaps that are extremely old or have been stored haphazardly lose their fragrance, and to varying degrees they will dry out. But they can be reconstituted with a touch of water. And the really good ones, regardless of age, will continue to produce excellent lather.

I've enjoyed some great vintage wines. I know enough to drink most of my purchases within a suggested window and few truly benefit from long term storage. I've been blessed to try some of these obviously past their prime (ahem) but still show a delicate, if frail greatness. I suppose, you make it right and it stays right. SIGH, back to plotting a lifetime cache' of my favorites for fear of disruption.

It's definitely how many months something can be opened. They are legally required to put it on but for soaps it really doesn't matter. Maybe the scent will decrease a little. In fact I've had B&M Leviathan since the original offering and each year it gets better. As someone pointed out perhaps for a croap or cream it will impact it after a year or so.

TL;DR: ignore it and happy shaving

Its not a "use by" date. Its called a Period After Opening (PAO) date. Its an EU cosmetics requirement. The date is "an indication of the period of time after opening for which the product can be used without any harm to the consumer." Essentially it means that the cosmetic product will perform as it should for the indicated time period after its been opened, if kept in normal conditions. It does not mean that it has gone "bad" by the end of the PAO.

My best guess is that the effective of soap is mainly dependent on the ingredients. I'll bet Mitchell's from the 1930's would work just fine. Some makers use ingredients that can spoil, such as avacado oil.

The two that I've had spoil were very stinky in a not good way.