Hi,
Its just an addition of resource to the machine , once ESXi is booted again it will detect the memory and add that in its resource pool. You have to just go with the hardware best practices i.e having same size of memory across DIMMs, if your DIMM slot one has 64 GB memory, use same size in the other DIMMs.There is nothing other specific to this and it can be removed always if it causes any trouble for you.