Hello,
1. Please specify your registered email account (send via PM), we will need to check your license status first.
2. On this page, you can see the difference between free/expired, standard and Ultra version of Player.
https://www.dvdfab.cn/media-player.htm?trackID=headmenu2#d1
Once trial expired, it will become a free version, and it doesn't support to playback regular DVDs.
3. Please attach a screenshot to show us the complete message when you try to play an .MKV file that is 3D and get the message saying Windows 7 not yet supported.
Also, in DVDFab Player 6, go to PC mode>Settings>Video section, and use the "Analyze Hardware" button to do the analyze and screen shot the result and send it to us. Thanks.