I bought the paid version of the script around 5-6 years ago, and I'm still getting access to the updates which is a really good sign and shows their commitment to their script and their customers.
The free sitemap generator is good as well for those that don't want to pay.
I use this site map software and think it's the best! They have a wonderful free service for map with up to 500 URL's that can be done manually which I actually used a long time until I found my site with thousands of pages of content to get indexed by the engines ;)
I highly recommend this company and their software!