When a post gets old, instead of simply closing the discussion, send comments and trackbacks to the moderation queue. This will greatly reduce spam.
For documentation and tips, please refer to the official plugin page for <a href="http://planetozh.com/blog/archives/2005/02/02/wordpress-plugin-auto-moderate-comments/" title="Auto Moderate Comments" rel="nofollow ugc">Auto Moderate Comments</a>

Ozh' Auto Moderate Comments

When a post gets old, instead of simply closing the discussion, send comments and trackbacks to the moderation queue.

Tired of regularly logging in and clicking the “Remember me” checkbox? No more. With this plugin, once 
you have logged in and until you voluntarily log out, your blog will remember you.
The ‘Remember Me’ checkbox on the login form will be always checked, and instead of logging you in for 14 days, the expiration is set to one year.
Related: for your localhost hacking, see plugin <a href="https://wordpress.org/extend/plugins/no-login/" rel="ugc">No Login</a>
<h3>Support</h3>
On <a href="https://github.com/ozh/always-remember-me" rel="nofollow ugc">Github</a>. I don’t read WordPress support forums.

Always Remember Me

Always checked 'Remember Me' checkbox and longer auth cookie expiration. Your blog will remember you.

Ozh' Auto Moderate Comments vs Always Remember Me