有效期
yoǔ xiào qī · HSK 7
period of validity
📅 有效期 = have (有) + effect (效) + period (期) = the period something stays effective
有 = have, 效 = effect/efficacy, 期 = period/term. Stack them: the span during which a thing has effect, i.e. its validity window or sell-by date. The 效 in 有效期 is the same 效 as in 有效 (effective).
有 — hand 𠂇 + moon/meat 月
Originally depicted a hand holding a piece of meat (月 here is the 'meat' radical, not moon), expressing the idea of possessing something. Over time the meaning broadened from 'to hold/possess' to the general sense of 'to have' or 'there is/exists'.
期 — 其 (phonetic) + 月 (moon/time)
期 is a phono-semantic compound. The right side 月 (moon) signals meaning, since lunar cycles marked fixed time periods in ancient China. The left side 其 supplies the sound. Together it points to a set time, period, or appointed date — meanings still carried today in words like 期间 and 日期.