A Personal subscription is not appropriate for your current usage (multiple commercial sites).
If you need to use Akismet on 10 or more commercial sites, you can choose the Enterprise subscription ($50/month or $500/year), which will cover an unlimited number of sites. Otherwise, check out our plans page for the subscription that fits you best.
You can contact the folks who helped you get up and running, and let them know that their Akismet API key needs to be upgraded. Or - simply choose to register you own subscription and activate the Akismet plugin using your new API key.
Yes. If you are currently using our WordPress plugin, go to the Plugins menu in your dashboard and click on the “Deactivate” link found directly under “Akismet.” If you happen to be using a different client, please refer to its documentation regarding deactivation. Note that your site(s) will then be left unprotected from spam, which is not recommended.