Every once in awhile it is okay to call, or in this case email.

This is the response I got when asking about Diamond challenge:

"Per your request, this specific Diamond Trial Offer that lasts until February 2014 will end on May 31, 2013.

The new Diamond Trial Offer which lasts until 2015 will begin in June 1,
2013. If you wish to utilize the later offer, please contact us on June
1, 2013 or later.