manger, fodder trough, horse barn
櫪 centers on a wooden structure for feeding or housing horses: a manger, fodder trough, or horse barn. The common thread is a wooden container or shelter associated with horses.
櫪 combines 木 (tree/wood) with 歷, which likely contributes the sound and may relate to passing through or sequence, but the exact historical motivation is uncertain. The character is used for wooden horse-related structures.
The left side is 木 (wood), and the right side 歷 looks like a complex structure with a roof and steps. Picture a wooden barn with a trough inside where horses eat: 櫪 is a horse barn or manger.
For レキ, imagine a horse named Reki who always eats from the wooden trough: Reki -> レキ, and the horse is at the manger.