WordPress.com has what’s called “Wordpress API keys”  These keys are very important to use the full power of  wordpress tools including Akismet while still hosting your blog away from wordpress.com somewhere else. 

How one can find his api key? Wordpress.com send this in your welcome email. Sometime this welcome email goes into your spam box and you may miss your api key, To avoid this you have to check your spam filter if it doesn’t show up in a few minutes.

Anyhow there is another way to find your api key. Here is step by step details

1. Go to wordpress.com

2. sign in with your login details

3.  Bring your mouse over the top left corner on My Account

Screenshots

4. A drop down menue will appeare then click on the edit profile

5. Here you can find your wordpress.com or wp.com api key