An important maintenance step is dealing with member status and type of those who fail to renew. If member statuses or types aren't changed, they may retain unwarranted access to organizational privileges, and you won't have current records on the overall status of your members. From the Manage expired members window you can process expired memberships throughout your database.
Note that this method makes use of the Paid Thru date in the member's record to perform the status and/or member type conversion. Most users will be set up with cash-based accounting (in Billing system setup), so this utility will work fine. If, however, you are set up for accrual-based accounting, and the Paid Thru dates are updated automatically at each billing, you'll have to convert expired member' statuses by hand, as needed because in some cases accrual updated Paid Thru at payment time.