By default members expire 1 year from when they pay (or on a Fiscal calendar date like April 1). Every member that is NOT on a yearly recurring payment cycle can have their Expiration adjusted manually. Members on recurring payment profiles are always considered in good standing (we assume they will re-bill automatically) so their expiration is un-editable.
To get started go to Board Member Dashboard > Members > Member Info
Or go to Board Member Dashboard > Members > Member Search
To Adjust a Member Expiration