Is there an episode where the sisters go back in time, and for a spell, it's implied they bought future illegal drugs?
I remember a line like "this would have been illegal back in our time", or something else with the word "illegal" in it.
But looking through transcripts of time travel episodes, I can't find it.
I think they bought it at an apothecary, but searching transcripts for the medieval time travel episodes for "apothecary" doesn't bring any lines that fit what I remember, although I'm not sure I read all the episodes.
And then there's how "apothecary" seems to have been only used in two episodes and neither are used for a medieval potion ingredients shop.