Found the below useful technical note provided by MicroStrategy in their Knowledge Base about ESRI Map Key stuff. Enjoy reading and using it when needed:)
There are three scenarios for using an ESRI key:
1. ESRI public maps :
User does not need a ESRI key if they want to run ESRI public maps. Users would not face any issues without a key in such a case.
2. MicroStrategy ESRI cloud offering :
User needs a key, which will be provided through MicroStrategy technical support if they want to use MicroStrategy’s ESRI cloud offering. Refer to TN45064 – How to activate ESRI for MicroStrategy Analytics Enterprise 9.4.1.
3. ESRI ArcGIS local server:
If user wants to set up their own ESRI ArcGIS server, then they need to get a key from ESRI and modify the esriconfig.xml file .