I read recently—unfortunately I can't remember where, or I'd link it—that when a creature uses its Legendary Resistance, that resistance lasts a minute. According to this, for example, if I cast Bestow Curse on Strahd and he failed the saving throw and used his Legendary Resistance, I couldn't put him under the effects of Bestow Curse for 10 rounds. Looking through the books I have, however, I can't find any reference to this.
How long does Legendary Resistance last?