Duly

wiktionary

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From Middle English duely, dewly, dulyche, dueliche, duweliche(“rightly, properly”), equivalent to due +‎ -ly.

etymonline

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duly (adv.)

"rightly, properly; adequately, sufficiently; in accordance with duty or moral obligation," late 14c., duweliche, from dewe "due" (see due) + -liche (see -ly (2)).