You have choices. 
First, your LightBurn key will work forever. And you are correct, the renewal does cost less than your initial license.
If you would like to continue to have access to our latest releases, the Renewal is the way to go. The renewal currently costs $30.00, adds 365 days to the expiry date, and is explained on our purchase page here: https://lightburnsoftware.com/products/renew-lightburn-license-key
As for changes, depending on how long you have been away…you may have some reading to do. 
We share the details here: https://lightburnsoftware.com/blogs/news This is a library of every release back to our Launch Day which was version 5.02 on December 30, 2017!