Use by date

I have an unopened bag of vanilla flavour powdeer dated 3/21 will it still be ok to have?

Yes it will be fine

I’ve used a few bags way past their dates without even noticing.

We obviously can’t sit here and tell you “Yes don’t worry, best before dates are rubbish”! But it is a best before, this means after that date it will not be as good, but not expired. Dan puts it best here:

As a few here have said, in their experience you’ll be fine.