Hi Lee. The short answer is yes. You will need to purchase a new license for version 3.x. Lloyd answered a similar question in the "License Question" thread. Version 3.x was a major update to WTP and LP.
"When you buy a license, it is good for any build that starts with the same Major number which is 3.x for Lamintion PRO, Woodturner PRO and 3D Design PRO. Since Segment PRO is new, it is Version 1.x. The build number follows the major number. For example, the build number for Segment PRO is 1.1.028.
If there is ever a major upgrade, it would be to 4.x and 2.x for Segment PRO. It is so hard to make a major upgrade, though, that I seriously doubt there will be a major release. All upgrades will likely be minor releases which will all be free to you."