Yes. When signing up for a NounPro or NounTeam account, you are signing up for a subscription that automatically renews each billing period. You can choose if it renews monthly or yearly. If for some reason you choose to cancel your subscription to a free account midway through your subscription, you still have access until the end of your billing period.
If you choose to cancel your subscription, your icon purchases and licenses are not affected. Read here for more info https://thenounproject.zendesk.com/hc/en-us/articles/203639098-If-I-purchase-an-icon-do-I-own-it-forever-