How "I" learn pieces by heart (or not!)

I've been singing & playing guitar solo and in duos, trios quartets etc,. since - maybe the '70s. I have a two door sideboard which is full to bursting with song "cheat sheets". I can't remember them. My hands remember the chord progressions, licks and fills better than I remember lyrics. This is partly due to my advanced age and lack of playing in 2017/19 (my cancer years), and 2020/21 (The Covid era) when the opportunities to gig pretty much disappeared.