Opencart Exclude Purchased Products from Search
This module excludes already purchased products from search results provided that you are logged in customer.
This module make required change via vqmod file and doesn't modify any core file.
Module is very easy to use, you just need to move given vqmod folder to your store root directory and make sure vqmod is installed and properly working on your store.
If there is a feature you want on your Opencart site, chances are that an Opencart plugin will allow you to do it, if you don't find any such plugin you can always contact us for your custom plugin development requirements.