What is the licensing system for ESXi?

Question

linux

There is 1 working machine with ESXi 5.1 (32gb RAM, 1 CPU Xeon x3450). In the near future it is necessary to raise the second server on ESXi 5.5 (DELL R710, 2 CPUs , 36GB RAM), the question is the following:
Is it possible to install ESXi 5.5 on a 2-processor machine without buying a license. As I read, vSphere is licensed for a physical processor, but you can do without it. I would like to know the nuances about ESXi. I'm still reading the documents on vmware.com, but maybe someone knows the answer)

Answer 1

the answer in the first link in Google for your request, did it not fully open your eyes?

Answer 2

5.5 U2 Free edition