Play method only ONCE when detected by the update function

Ok, first off your using a Update method, which it's going to be called every frame if Peeker is enabled. Second you should use a tick method;

 void Test()
 {
 bool ticked; 
 if(ticked && Peeker.GetComponent<PeekerDie().enabled)
 {
 ticked = false
 // Run code here
 }
 else if(!ticked && !Peeker.GetComponent<PeekerDie().enabled)
 {
 ticked = true
 }  
 }

If this need revisions, or this doesnt work, just comment.

Note: This can be runned multiple times, if you dont want that remove the else if statement, and set ticked to true. Also, this can be used in an update method, but the ticked will keep switching to true and false, if peeker is also enabled or disabled, you can run void Test on Update.

 // has the method been run already?
 public bool hasAppliedKillForce;
 
 void Update()
 {
     if (Peeker.GetComponent<PeekerDie>().enabled == true && hasAppliedKillForce == false)
     {
         // use a coroutine
         StartCoroutine(applyKillForce());
     }
 }
 
 IEnumerator applyKillForce()
 {
     // do something
     // ensure coroutine can not be triggered again
     hasAppliedKillForce = true;
     yield return null;
 }

https://docs.unity3d.com/Manual/Coroutines.html https://docs.unity3d.com/ScriptReference/Coroutine.html

int killForceCount = 0;

Update() { If(killForceCount == 0 && your condintion ) {

killForceCount++;

ApplyKillForce();

} } Just add a counter variable and add one to it each time you call the function. If you only want to call it 3 times for example then you would say if count is less than 3 call the function. Otherwise don't. :) sorry for the sloppy code writing on my phone.