Hi, a normal lip cold sore should heal up in about 2 weeks from scabing over to gone, however, depending on the person skin type it may leave a spot/scar. Maybe she even ate some food or a drink that is acid based that prevents complete healing. But at this point if there is no open broken skin it would not be contagious after a month.
She might take a herpes blood test just to confirm she does in fact have oral herpes.
Did the inflammed red blotch ever go away ? If so how long did it take ?