Lion (Mac OS 10.7.x)
If you are on Lion (Mac OS 10.7.x), Design 3D CX 6.x may not retain your serial number - but there is a solution.
Apple has made some changes in the operating system starting with 10.7.x, having to do with where and what our application can write. We've made some changes to compensate for this in Design 3D CX version 7.x, but until you're ready to upgrade, there is a workaround for this issue.
The workaround requires changing the permissions on the system wide preferences folder, temporarily:
-Locate the following at the top level of you hard drive, Library > Preferences.
-Select the Preferences folder and Get Info on it. At the bottom of the Get Info dialog in the Sharing and Permissions area, change "everyone" to Read & Write. (You might have to click the Lock icon in the lower right and authenticate with your (admin) password)
-While "everyone" is set to Read & Write, launch Design 3D CX 6, enter you serial number and user info. Then quit and relaunch Design 3D CX 6. You should not need to enter the serial number on the second launch.
-Now, you will want to change the permissions for "everyone" back to Read Only for that Preferences folder.
You should no longer need to enter the serial number when launching Design 3D CX 6.
Mountain Lion (OS 10.8.x) and Mavericks (OS 10.9.x)
If you are on Mac OS X 10.8.x or 10.9.x, Design 3D CX 6.x will not retain your serial number, but there are a couple of solutions.
1) Upgrade to Design 3D CX 7.5 - this is the best solution.
2) Send your serial number to Strata support and we can provide you with a file and instructions on where that file goes so that you don't have to enter your serial number on each launch of Design 3D CX.