Today we saw an online article where a well known financial institution unintentionally allowed its domain name to expire. (Reference - "Regions.com update: domain renewed, but access remains limited"). This can not only be embarrassing, but can result in loss of connection with your customers or clients. A lapsed name can typically be renewed for a limited or no penalty for 30 or 45 days, but why take that chance?
To check your expiration date perform a Who Is Lookup. Google likes to see dates that are more than a year out so renew for 2 or 3 years and then you won't risk an accidental domain name expiration.