When we dream the chemicals in our brain designed for converting memories to long-term storage are suppressed. This is why we don't recall our dreams very well.

Most vivid dreams occur during the later REM cycles, usually the period right before we wake. This helps us remember them better. These dreams also last longer than dreams earlier in the night.

Practicing dream recall is best done immediately upon waking, when the visions are still in our mind and we can still connect to the REM cycle we were dreaming in. If we don't get these memories converted to long-term storage they will simply fade out. Lucid dreams are no exception; if you don't practice recall efforts the lucid dream will disappear or fade like any other dream. Our awareness in a LD does not give us additional advantage at remembering it. The events in the dream are more likely to be remembered because of their unique status and the fact we typically wake during or right at the end of a lucid dream, but without making the effort to recall it the dream will fade like any other.