How much memory does your ESXi has? If you haven't set up any special configuration for the Windows VM, the ESXi server will use the common overcommitment techniques with the VM. If you have more than 32 GB of RAM on your ESXi box, you will never be overcommited (assuming your other VMs are powered off). So the ESXi will give physical memory access to your Windows VM as long as it requests for.
You can also guarantee physical memory for the VM using reservations, if you want.