You can make a one-time request for an absentee ballot or you can request an absentee ballot for all elections. If you choose to receive a ballot for all elections, you're on the list for good! The only way your status would drop is if you move and do not notify the elections office. You must be a registered voter to request an absentee ballot.
If Election Day is growing near and you still have not received your ballot in the mail, contact your local election office. They'll be able to look you up and provide you with your voting options. The deadline to request an absentee ballot is 12:00 noon the day before the election, and the deadline to submit your voted absentee ballot is 8:00 p.m. on Election Day.