If you already have a key or a newer license, you can try these official routes:
VMware ESXi 5.5 is a that reached its End of General Support (EOGS) in September 2018 and End of Technical Guidance in 2020. 🛡️ Licensing and Availability license key vmware esxi 5.5
It could not be managed by vCenter Server. Without vCenter, premium features like vMotion and High Availability (HA) remained locked. If you already have a key or a
VMware offers several types of licenses for ESXi 5.5, including: license key vmware esxi 5.5