Keys pressed in specific order

The following code has not been tested and may be too complicated or too complete, but will cover your needs. I've commented it to be as clear as possible

 // Specify the keycodes in the inspector
 public KeyCode[] KeyCodeSeries = new KeyCode[] { KeyCode.Alpa1, KeyCode.Alpha2, KeyCode.Alpha3 } ;
 
 // Use this if you want the user to press the series of keys in a given times interval
 public float DelayBeforeReset = 86400; // = One day
 
 // Specify in the inspector the function you want to call
 // after the series have been completed
 public UnityEngine.Events.UnityEvent OnSeriesComplete;
 
 // Specify in the inspector the function you want to call
 // after the series have been failed because a wrong key has been pressed
 public UnityEngine.Events.UnityEvent OnSeriesFailed;
 
 // Specify in the inspector the function you want to call
 // after the series have been failed because the user did not pressed the key before the end of the delay
 public UnityEngine.Events.UnityEvent OnTimeRunnedOut;

 // The index in the array of the next key to press in order to continue the series
 private int keyCodeIndex ;

 // The time (in seconds) the last correct key has been pressed
 private float lastKeyPressTime;
 
 private void Update()
 {
     // Make sure some keys have been specified in the inspector 
     if( KeyCodeSeries.Length == 0 )
         return ;
 
     // Check if the user pressed the key before the end of the timer
     if( Time.time - lastKeyPressTime > DelayBeforeReset )
     {
         keyCodeIndex = 0 ;
         if( OnTimeRunnedOut != null )
             OnTimeRunnedOut.Invoke();
     }
 
     // Correct key pressed!
     if( Input.GetKeyDown( KeyCodeSeries[keyCodeIndex] ) )
     {
         lastKeyPressTime = Time.time;
         keyCodeIndex++ ;
 
         // Series completed!
         if( keyCodeIndex >= KeyCodeSeries.Length )
         {
             if( OnSeriesComplete != null )
                 OnSeriesComplete.Invoke();
             
             // Reset index to allow to start again
             keyCodeIndex = 0 ;
         }
     }
     // Wrong key pressed!
     else if( Input.anyKeyDown )
     {
         keyCodeIndex = 0 ;
         if( OnSeriesFailed != null )
             OnSeriesFailed.Invoke();
     }
 }