Newer version

I have SmartFTP v4.0.1072.0 and the updater says the newest version is 4.0.1222.0. May I update for free or will I have to pay for the update?

I don't know how to find the serial number. I did find this in the About window, does that mean maintenance ended in 2010? I thought updates were free until a new major update like version 5.