subscription, buy
購 centers on acquiring something by paying money: buying or subscribing to a service. The subscription sense is a specific form of purchase, often recurring.
購 combines 貝 (shell, money) with 冓, which likely contributes the sound. The shell radical indicates a financial transaction, giving the meaning of buying or purchasing.
The left side is 貝 (shell, an old form of money), and the right side 冓 looks like stacked goods. Imagine using shells to buy a stack of items: that's purchasing.
For コウ, picture a coin dropping into a machine to buy a subscription: the clink of the coin sounds like 'koh' (コウ).
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purchase; buying
buying and reading (book, magazine, etc.); subscribing (incl. free subscriptions); taking (e.g. newspaper)
procurement; purchase; buying
environmentally responsible purchasing; green purchasing
lump-sum purchase; bulk purchase; group purchase
subscription
advance purchase (e.g. fare)
advance purchase excursion fare; APEX fare
(former) National Association of Purchasing Management (USA); NAPM
cooperative buying; group buying; joint purchase
buying in installments; buying in instalments
instant purchase; buying immediately
subscription (e.g. to a magazine)
direct purchase
stock option
to buy; to pay for
purchase price
retailer
purchased item; purchased goods; (a) purchase
purchase date