Hi Anmol thanks for posting in the Lucid Community. It sounds like you are referring to the icon search feature in the Shapes section to the left of your canvas. This allows you to perform a keyword search to find and import icons from Iconfinder (or images from Bing or GIFs from Giphy). As we do not host or control these search results you will need to check the copyright permissions for any content you find there. Users are ultimately responsible for making sure they have the proper permissions or licenses to use any images icons or GIFs available online.
If you are worried about the copyright permissions of icons you find in the search results I would recommend using a search engine that allows you to filter for results that are in the public domain. Hope this helps!