c. 1300, "booth or shed for trade or work," perhaps from Old English scoppa, a rare word of uncertain meaning, apparently related to scypen "cowshed," from Proto-Germanic *skoppan "small additional structure" (source also of Old High German scopf "building without walls, porch," German dialectal Scopf "porch, cart-shed, barn," German Schuppen "a shed"), from a root *skupp-. Or the Middle English word was acquired from Old French eschoppe "booth, stall" (Modern French échoppe), which is a Germanic loan-word from the same root.
The meaning "building or room set aside for sale of merchandise" is from mid-14c. The meaning "schoolroom equipped for teaching vocational arts" is from 1914, American English (as in shop class, attested by 1948).
The sense of "one's own business, craft, or calling" is from 1814, as in talk shop (v.), "converse in general society about matters pertaining to one's trade," which is attested by 1860. Shop-talk (n.) is by 1881.
c. 1500, from adjectival use of past participle of wear (v.); from Old English geworen. Worn-out "exhausted by wear, made ineffective by overuse" is attested from 1610s in reference to things, c. 1700 in reference to persons.
<a href="https://www.etymonline.com/word/shop-worn">Etymology of shop-worn by etymonline</a>
Harper, D. (n.d.). Etymology of shop-worn. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/shop-worn