I am new to HubPages, too, and definitely the wrong person to ask. But, if validation is required as your question implies, it is the first I have heard of it. Take heart though, many programs such as Office have a tool for giving accurate word counts on written materials. Check the program(s) you use, and I am sure one or more will have that tool available.
On HubPages there is a counter showing automatically at the top of your pieces where you are clicking "Done Editing."
Now a question for you from me: where did you read about "validate the word count" and didn't that reading tell you how and when?