Why does Copyscape allow a limited number of searches for my site?
Copyscape’s operations take up significant bandwidth and computation resources, so we are only able to provide a limited number of searches in the free service. If you would like to perform more than 5 searches for your website per month, sign up for Copyscape Premium, which allows thousands of searches per month. You may see a message indicating that this limit has been reached even though you have not performed too many searches on a certain site – this simply means another person has already exceeded the limit for this site. In such a case, you may use Copyscape on another site, or sign up for a Premium account.