The file you need to be using to install the 767-300 Base Pack is named csx767_1500.exe!
If you bought the Boxed version from Aeosoft, or a download version from one of the other online stores, you are able to check in to your profile an download the latest version. I would have thought that they all would already be up to date, except for AS and their boxed product (old stock). So please make sure that is the one you are tying to install version 1.5 (csx767_1500.exe).

I haven't heard of anyone having the demo mode problem with the 767-300 Base Pack v1.5.

Mark