If you absolutely need to run ESXi 5.5 for legacy reasons and you have an original, valid license key from VMware, use that – but understand the risks. Otherwise, invest your time in migrating to a current platform. Your future self (and your security team) will thank you.

What (server model, CPU) are you trying to host this on?

: Allows virtual machines to have up to 8 virtual CPUs (vCPUs).

Navigate to the or Licensing section How-To: Install a Free License Key for ESXi . Select "Assign License" and enter the 25-digit key. Why You Should Migrate Away from ESXi 5.5 in 2026

VMware ESXi 5.5 is a bare-metal hypervisor that enables users to create and manage virtual machines. To use ESXi 5.5, organizations need to purchase a license, which grants them access to the software and its features. VMware offers various licensing options, including free, paid, and trial licenses.

After the 60-day evaluation period, or even before it ends, you can convert your ESXi host to using a free, perpetual license key. This free edition is officially called the VMware vSphere Hypervisor .

: Fresh installations of ESXi 5.5 default to a 60-day evaluation mode , providing full feature access before a key is required. Important Modern Changes

: Technical guidance concluded on September 19, 2020 .

A powerful, Debian-based enterprise virtualization platform utilizing KVM and LXC. It features a robust web GUI, built-in backups, and clustering.

Running ESXi 5.5 in a modern IT environment introduces severe operational vulnerabilities: Unpatched Vulnerabilities