Input.GetKeyUp
static function GetKeyUp(name: string): bool;
static bool GetKeyUp(string name);
static def GetKeyUp(name as string) as bool
Description

Returns true during the frame the user releases the key identified by name.

You need to call this function from the Update function, since the state gets reset each frame. It will not return true until the user has pressed the key and released it again.

For the list of key identifiers see Input Manager. When dealing with input it is recommended to use Input.GetAxis and Input.GetButton instead since it allows end-users to configure the keys.
	function Update () {
		if (Input.GetKeyUp ("space"))
			print ("space key was released");
	}
using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Update() {
        if (Input.GetKeyUp("space"))
            print("space key was released");
        
    }
}
import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def Update() as void:
		if Input.GetKeyUp('space'):
			print('space key was released')

static function GetKeyUp(key: KeyCode): bool;
static bool GetKeyUp(KeyCode key);
static def GetKeyUp(key as KeyCode) as bool
Description

Returns true during the frame the user releases the key identified by the key KeyCode enum parameter.

	function Update () {
		if (Input.GetKeyUp (KeyCode.Space))
			print ("space key was released");
	}
using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Update() {
        if (Input.GetKeyUp(KeyCode.Space))
            print("space key was released");
        
    }
}
import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def Update() as void:
		if Input.GetKeyUp(KeyCode.Space):
			print('space key was released')