UPDATED AUG 15, 2011
CREDITS - you can take for your own use but you must keep the credits intact.In other words, do not claim as your own. You cannot remove the theme credits link no matter how much you customized it.
You can choose to remove the button and have a text link instead if you know how to edit HTML. Otherwise, contact me about it and I can do it for you.
PARTIAL-ALTERING ALLOWED - you can alter some the HTML codes. Partial-altering means that you cannot alter it to the point that it is no longer recognizable as my theme.
I know some of my earlier tumblr premades, you cannot customize it a lot so you have my permission to alter the codes (including hex colours for backgrounds, links, image backgrounds, fonts, date format etc). However, you still have to credit me. It is still my base codes, thus, still my theme.