Final answer:
The gerund 'promising' in the sentence functions as the direct object of the verb 'remember.'
Step-by-step explanation:
The gerund in the sentence 'I don't remember promising to take you to laser tag.' functions as a direct object. Specifically, it's the object of the verb remember. Gerunds are verbs that end in -ing and act as nouns within a sentence, taking on various roles such as subjects, direct objects, subject complements, and objects of prepositions. In this case, promising is the gerund and is part of the gerund phrase 'promising to take you to laser tag,' which is being remembered (or rather, not remembered) by the subject of the sentence.