gTLDs Domains are leased on an annual basis, and need to be renewed once the current payment for the lease expires.

For example, if a domain is registered on January 1st 2006 and prepaid for one year, it will be
due for renewal on January 1st 2007, at which point the registrant either pays for additional years, or lets the name expire.

Domains can also be pre-paid for multiple years, up to a maximum of 10 years.