I'm John O'Neill with SourceGear, the company that made the free Vault Pro offer.
You're quite right -- the page had an error this morning, stating that the offer was good through June 30th. We corrected that as soon as we noticed it, and now the page reads, "This offer is good until August 30th."
Anyone who requested a voucher for their free licenses before the correction will have no trouble redeeming it. The only error was in the wording on the download page.
Sorry for any confusion. I'm happy to answer any questions about the free Vault Pro licenses. You can reach me at firstname.lastname@example.org.