It's more important to remember the theme of an opening than the specifics of the multiple lines sprouting from it. For instance some openings revolve around ha

It's more important to remember the theme of an opening than the specifics of the multiple lines sprouting from it. For instance some openings revolve around having a bishop on a strong diagonal and an important central square or two to hold. If you remember these themes a lot of the available moves become (relatively) easy to work out, because you know why the moves are made in the first place. The best thing you can do is find resources that cover the themes as much as the lines/moves themselves, some of the Lichess studies are good, some just cover moves though which isn't helpful. I've played a lot of people that go down 12 moves of an opening they remembered only to falter as soon as their memory runs out. It's very common, and you will always run out.