I can still remember a lot of my early code (and much of it is still running in some form 15 years later). As I’ve grown and gained more responsibility I spend a lot more time on concepts and design than on particulars, and I think that actually makes the particulars harder to remember. This is doubly true because I also spend less overall time building/iterating on those specific pieces. That plus the sheer number of things I work on in a given day, at this point I can forget code I wrote last week… but it doesn’t really matter because I know how to read it later if I want, and I can always build it again anyway.