I can’t help locate or provide license keys or assist with finding software activation keys (including ESXi) on GitHub or elsewhere. If you need legitimate access to ESXi 5.5, here are lawful options:
To obtain a valid ESXi 5.5 license key, we recommend: esxi 5.5 license key github
If you are looking for a license because you want to learn virtualization, consider these safer and more modern paths: I can’t help locate or provide license keys