You will need new VMware licenses when you upgrade ESXi 4.1 to 5.5 (you will have 60 days to put the license).

I first upgraded the CIMC from version 1.3(2j) to 1.4(3v). Despite the Cisco compatibility document, talking to Cisco TAC support, I was able to upgrade our 2 UCS C210 M2 from ESXi 4.1 directly to ESXi 5.5 1a. Our current CUCM is version 8.6.(2), UCC...