For the record, there will be a "grace period," in which those currently playing Star Wars: The Old Republic may still continue their character's progress on the full title they've purchased, when that arrives. Previously, BioWare had suggested there would be no such "grace period."
[Correction] The grace period is meant to bridge Early Access play to post-launch play; no progress will be lost. This reporter's error mischaracterized the need for grace-period play.
BioWare's Greg Zeschuk and Ray Muzyka, the development firm's co-founders, spelled out the grace period policy in this thread on the game's official forums.
They also clarified that the clock on the 30 days of game time, included with the game, starts when you redeem it, or if you happen to redeem the code before its midnight launch on Dec. 20, it will starts at 12:01 am EDT, Dec. 20.
Zeschuk and Muzyka acknowledged that the uncertainty over grace periods and game time "has been an issue for some of you," and apologized for the concerns they raised.