Does it have a yearly licence setup or is the software just a single purchase that you have forever (or until you decide to upgrade to 4.0 if that comes out)?
You can use v3.x forever without buying anything else
Can I buy it and install fences on my laptop and desktop using the same licence and expect it to work?
You can use one license on five PCs
I have 2.13 (2.0) atm. Do I need to uninstall 2.0 first or can i just install 3.0 from the bundle and it will just keep all my settings from 2.0 and work out the uninstall itself
You should uninstall and your setting will carry over
On the note of upgrading, can i still use my old (current) 2.0 license on my laptop for example or would the upgrade to 3.0 void the 2.0 installer?
2.0 licenses are still valid if you want to use them on other PCs.