Upgrading ESXi License to 6.5 - Will current ESXi 5.5 VMs still function?

Hello,

If I upgrade our vmWare ESXi 5.5 license to 6.5 in preparation for upgrading our ESXi servers, will the ESXi 5.5 servers continue to function while we are transitioning to 6.5?

It could take up to a month before the 5.5 ESXi servers are upgraded after the License Key is upgraded.
Would the ESXi 5.5 servers still run? Would it be legal by vmWare standards to continue to run our 5.5 servers while preparing to move to 6.5?

Thanks,