This is a pretty new development. Akismet is not free anymore – but they do have a free version for “personal” use (well, it’s listed as “pay what you want”).
If you see this error then don’t panic. For that matter, in general, don’t panic. I think for now you can leave things as-is and my guess is that it will just keep working for a good long while. Till they decide to get more strict.
Better yet, do as I did and start paying them for this excellent service. Go to http://akismet.com/plans/ and sign up for a free plan – pay what you want – or a paid plan. You can make an account with Akismet or use a wordpress.com account.
And for all my clients that don’t host their WordPress sites with me, I suggest paying extra for the Akismet and VaultPress bundle. VaultPress provides a very powerful backup and security scanning service.
- WPtavern account set-up with screenshots