Support have sent out a mass mailing about this Steam authentication issue:
Hi there CMDRs,
This is part of a mass response to those affected by the current "Please Purchase/Redeem" issues.
We have investigated this issue, and it looks to be due to an authentication issue through Steam. This should hopefully be resolved soon, and once it has been resolved, you will be able to play.
Should you have any questions, let us know. We should be back to normal soon!
Here's hoping - in the meantime my Blue-Rays of BBC's 2 "Smiley" series have arrived today - great image quality so I will just do that instead.