This module is designed to repair missing fields from various commerce entities. After installing, visit the menu item that does the repair, admin->store->config->Repair Commerce Fields (admin/commerce/config/repair). Once you've done that you can uninstall the module.
If you're using a Commerce dev release after 3 November 2011, you don't have to patch Commerce at all. Earlier versions of Commerce require this patch to Commerce, which is now incorporated in the code.