To maintain security, limit data retention, and protect the privacy of our users, WhatsApp accounts are generally deleted after 120 days of inactivity. Inactivity means the user hasn’t connected to WhatsApp.
An internet connection is required for an account to be active. If a user has WhatsApp open on their device, but they don't have an internet connection, then the account will be inactive.
Content stored locally on a user’s device prior to account deletion will remain until WhatsApp is deleted from the device. When a user reregisters for WhatsApp on the same device, their locally stored content will reappear.