Yes you need ESX or ESXI ver 4.1 or above to for UCS server. Over ESXI you can deploy MSE Virtual appliance.
Moreover Location services license supports RTLS and RFID. To support 1500 AP's you have to purchase to two
Cisco MSE High-End Virtual Appliance with 1000 and 500 AP Location service license. You can also setup HA on MSE.
For installation and HA configuration, please follow the below link.