She has managed to prove his place as the spy of the Order since before he let the Death Eaters into the school of wizardry, and once the whole truth came to light, he was pardoned and even awarded the Order of the Merlin for his part in the victory, not only because of the information he provided but also for his part in the duel between Harry and Voldemort, where Malfoy covered the chosen one's back before he managed to deal the final blow to the Dark Lord.