age
齡 centers on the concept of age, specifically the number of years a person or thing has existed.
齡 combines 齒 (teeth) and 令, which likely contributes the sound. The tooth component relates to the traditional practice of determining age by examining teeth, especially in animals.
The left side 齒 shows teeth, and the right side 令 looks like a person kneeling under a roof. Imagine counting teeth to determine someone's age, like checking a horse's teeth.
For レイ, picture a ray of light shining on a set of teeth to reveal their age: ray -> レイ.