Yes, it is.

You can read the full details in the agreement that you accept by downloading Lightstreamer Moderato: http://www.lightstreamer.com/distros...0Agreement.pdf

You can learn about the limitations of the Moderato edition in the product matrix: http://www.lightstreamer.com/products
For example, you get max 1 update per second for each subscribed item in the page; and you only get the JavaScript client library (anche the Flash bridge, if needed).