How to load single COM instance for multiple application instance

I'm creating a COM dll and it will be loaded by VBA. However, I noticed that for ever开发者_如何转开发y excel instance (workbook), a new COM object is loading to memory. But I need to maintain single COM state irrespective of number of Excel instances exists.

Please help me achieve this purpose .

Thank you

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Maybe this will help you:

Implementing the Singleton Pattern in C#