Parole is a conditional release. If you have served the maximum possible prison term for your offense, then there would be no basis for imposing conditions as you would not be subject to being returned to prison.

For example, if the maximum penalty for a specific felony was five years in prison, and you served five years in prison thereby maxing out your sentence, you would be released without parole. If you were sentenced to three years, you could be placed on parole subject to being returned to prison for up to the two remaining possible years of incarceration.