C++ Singleton design pattern

Recently I've bumped into a realization/implementation of the Singleton design pattern for C++. It has looked like this (I have adopted it from the real life example):

// a lot of methods are omitted here
class Singleton
{
   public:
       static Singleton* getInstance( );
       ~Singleton( );
   private:
       Singleton( );
       static Singleton* instance;
};

From this declaration I can deduce that the instance field is initiated on the heap. That means there is a memory allocation. What is completely unclear for me is when exactly the memory is going to be deallocated? Or is there a bug and memory leak? It seems like there is a problem in the implementation.

My main question is, how do I implement it in the right way?

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Being a Singleton, you usually do not want it to be destructed.

It will get torn down and deallocated when the program terminates, which is the normal, desired behavior for a singleton. If you want to be able to explicitly clean it, it's fairly easy to add a static method to the class that allows you to restore it to a clean state, and have it reallocate next time it's used, but that's outside of the scope of a "classic" singleton.

---

You could avoid memory allocation. There are many variants, all having problems in case of multithreading environment.

I prefer this kind of implementation (actually, it is not correctly said I prefer, because I avoid singletons as much as possible):

class Singleton
{
private:
   Singleton();

public:
   static Singleton& instance()
   {
      static Singleton INSTANCE;
      return INSTANCE;
   }
};

It has no dynamic memory allocation.

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