Who Can Register-You can register to vote if you are a citizen of the United States, a resident of the State of Oklahoma, and 18 years old or older.Felons-A convicted felon may not register for a period equal to the time of the original sentence.A convicted felon who has been pardoned may register.ligibility. Who Can Register-You can register to vote if you are a citizen of the United States, a resident of the State of Oklahoma, and 18 years old or older. Felons-A convicted felon may not register for a period equal to the time of the original sentence. A convicted felon who has been pardoned may register.