Wrong. In Chile, Pinochet and his henchmen pardoned themselves before leaving office. Northern Ireland terrorist prisoners have not been pardoned, and they certainly are not in a position to pardon themselves.
They are only being released on licence. Their convictions still stand.
If their organisation re-offends, they will have to return to prison to complete their sentences. Punishment beatings, not part of the ceasefires, continue to be investigated, and their perpetrators will continue to be tried and punished if found guilty; as are any breaches of the ceasefire and crimes by organisations not party to the Good Friday agreement.