The response we have obtained from the German VALEO Laboratory is as follows:
"In Germany the law says, everything you eat (or inhale) has a maximum expiring date of 24 month.
E-Liquids actually should have no expiring date, because as long as you store them closed, cool and dark,
nothing expires. It is like with a tin can of soup, you could still eat it in 50 years, but the producers have to print an expiring date of 24 months on it.
So you can tell your customers, they still can use these liquids.
Your liquids might get darker in the meantime, this is from the UV-Light, the nicotine reacts with that, but this has no influence on the taste."
So you can vape them perfectly fine.