A lick and a promise
From Heavens to Betsy! & Other Curious Sayings, Charles Funk:
The "lick" pertains to the rapid lapping of the tongue; it’s a small quantity of a small amount, about the amount we mean when we say that so-and-so hasn’t "a lick of sense." The "promise" is of something which might be long deferred. The expression dates back at least to 1850.
From A Hog on Ice & Other Curious Expressions , Charles Funk:
The saying is common in both England and America, and is undoubtedly several centuries old, but examples of literary use are not recorded. <huh?>
Other licks:
Lick into shape
From Hog on Ice
The saying comes from the ancient belief that:
"Beres ben brought forthe al fowle and transformyd and after by lyckynge of the fader and moder they ben brought in to theyr kyndely shap." -- The Pylgremage of the Sowle, de Guilleville, as translated in 1400.
The belief probably arose from the fact that bears cubs at birth are hairless and very small, and the mother usually keeps them concealed for four or five weeks.
From Why You Say It, Webb Garrison:
Totally without foundation but circulated for at least a thousand years, beliefs about bear cubs lead us to say that when we’ve mastered a difficult situation or made something presentable, we have licked it into shape.
One’s best/solid/good licks
From Hog on Ice:
"Lick" in American speech came to mean a spurt of speed or burst of energy, and the phrases best/solid/good licks arise from that meaning.
"I saw comin’ my gray mule, puttin’ in her best licks, and a few yards behind her was a grizzly." -- Polly Peablossom’s Wedding, TA Burke (1851).
From me:
I’m guessing that the speed sense of lick is the basis for the phrase lickety-split.
