Every 5,000โ7,500 miles or 6 months, whichever comes first โ check your manual, modern synthetics last longer than the sticker says. Squirrel it by date; your odometer doesn't send reminders.
Yearly, with a real deadline and a real ticket if you miss it. Many states let you renew online in 5 minutes โ the task is remembering, and the sticker.
Go check your expiration date right now โ it's usually your birthday in some year you haven't thought about. Squirrel it with a 30-day lead; REAL ID renewals can require an office visit and documents.