i have a question, I want to buy Dell PowerEdge T330 and I can choose from these 3: VMware ESXi 6.0 U2 Embedded Image on Flash Media VMware ESXi 6.5 NFI VMware ESXi 6.5 U1 Embedded Image on Flash Media
my question is, do I need to buy another license to install and use VMware vCenter Standard?
These options don't give you the license. They represent what will be installed from the factory with the typical 60 day trial.
You can use this with a 'free' license, or any of the purchased licenses (keys).
If you want to buy the VMware license with the server as well, look further on on the website where you're building the server to find the OS license and VMware support contract (1 year minimum is required).