Finally I got a free Reflector Ver 6 after I register with a key from Red-Gate. The redgate posted a message that It will not expire or force you to update for this version. I've used it for around one month and I haven’t got any disturbing messages yet.
You can register by using the link on the Disassembler window or help menu. You will get received an email with a serial key as soon as you register it. (This serial key can be used to active up to 5 machines.)
Unfortunately there is no separate download link for this version. Only available to existing users of the free edition and the update mechanism will update to the 6.8 version. I cannot guarantee you all things work well so your reflector may be upgrated to version 7.
[2011.07.27]
I sent the my reflector folder(contains files) (Ver 6.8) to one of my colleagues and she executed it then activation / registration window popped up so she could register using the register button. Look for the version 6.8 near around you then you will get the last free version.