If I purchase Norton 360, and upon its expiry I do not renew, do I still have access to my online backup storage after the subscription expiration? Can I still access my data if I don’t renew?

With the expiration of your Norton 360 subscription, you also lose your online storage space together with your data. While Norton LifeLock may keep your data for a certain number of days after the expiration (giving you a chance to retrieve your data if you subscribe to the service again), there is no guarantee the data will not be purged at any time following the expiration (this is as per Terms & Conditions of Norton Online Backup: Data stored to the online backup space provided with Your Service will be at risk of being purged).