I am searching the web site for the end user license for PROTEXT 2.X
and 3.X but I could not find it.
There is no single license. Protext is a collection of thousands of
packages with different license terms. The intent is that it is all
free (libre) software, along the lines of TeX Live, but we cannot give
you legal guarantees of anything.
Protext is essentially MiKTeX with a few additional tools. So what you
really need is an answer for MiKTeX -- see www.miktex.org.