ehm....
"Upgrading for licensed users
If you already own a license for AC3D, download and install the new version of AC3D from here. Start AC3D and enter your current license-key in AC3D's menu, Help->Enter-License-Key. If you purchased AC3D during or after December 2008 , the upgrade is FREE. If you have an earlier license key, you can upgrade for just $34.95 - for a limited period. " from there:
http://www.inivis.com/downloads.html
Sorry, haha lol? Andy but you want take more 35$ for mouse scroll in Linux and 2-3 minor bugfixes? its fair yeah?
I waiting add mouse scroll for Linux version in 2(two!) f*cking years, but now ill must pay more again for this "major" feature? Nope. Its called "small bugfixes" and 'some minor changes".
Yes, i can understand about pay upgrades from version 4 to 5 , from 5 to 6 - its called " new version, major changes etc.." but... but from 6.5 to 6.7? o_O ?
"Autodesk style upgrade" now migrate to middleware soft? lol. if is it: bye-bye proprietary Inivis, welcome Blender=). IMHO