Download the official Wordfence security plugin from: https://en-ca.wordpress.org/plugins/wordfence/ Upload the plugin to your wordpress ...
You should see:
Now right under it paste this in:
So the code should look like this:
7. Save the file, then activate WordFence plugin, you should have unlimited premium license! It says "renew in 365 days" but you will notice that this number doesn't go down