To get access to Minecraft premium via Cookies, visit the Chrome Web Store and download Edit this Cookie extension. Install it and click on the button added on top of your browser to open it.
Now, open the Minecraft website and then head to Edit this Cookie extension. Delete existing cookies and hit the import button if you have got the premium Minecraft Cookie data.
Many websites offer Minecraft premium cookies for free. You can get the data by visiting such websites and paste the copied Cookies. Finally, click on ok and refresh the Minecraft website.