Usually itīs a best before date not an expiry date. When the tube is open, bacteria and fungi can start to grow into the tube. So it should be used up within a couple of months once it has been opened.
I was really surprised to find a best before date on a box of talcum powder. Who would have guessed that ground stone might turn bad?
If it isnīt broken, it doesnīt have enough features yet.