To get a free license:

The most important change is that . In previous versions (6.7, 7.0, 8.0), you could obtain a legitimate "Free Hypervisor" license key directly from VMware. That program has ended, which is why many users are now searching GitHub for alternative ways to activate the software. 2. Why "GitHub Portable" Keys are Risky

If you want "portability" – running ESXi as a VM inside another hypervisor – this is possible legitimately:

To run ESX 9.0, your environment must meet these new architectural requirements: Unified Appliance : Both VVF and VCF 9.0 are deployed using the unified VCF-SDDC Manager Appliance License Management : You must install VCF Operations

Alex decided to purchase an official VMware ESXi 9 license key from an authorized reseller. The process was straightforward, and the new key was activated without any issues.

This remains the most reliable legal method for "portable" lab use. A VMUG Advantage membership