Hi Andy,
Welcome to the forum.
You will find there are members who rely only on WL to drive their websites. Most use either WD or VWS and some use both with the help of VirtualVP from Softwx. But to answer your question, you will need to buy any of those programs.
It is a shame that Davis doesn't market WL as a free program bundled with the necessary DataLogger.
Enjoy,
George