I know I forgot an LD because I woke up right after and remembered it in the middle of the night, but I was too lazy to write it down, and then by morning the details were gone, just like a regular dream that you sort of half-remember, but slips away even as you are thinking about it. All I remembered was that at the time I thought it was my best longest one yet.

Also, once in the morning after I woke something reminded me of a dream I had the night before, and then suddenly this whole lucid dream I had came back to me. So I could potentially have never remembered that one.

So I'm sure I've had them and forgotten them.