Install the "Edit this Cookie" extension in your preferred browser. In this method, this extension will be really handy.
After the installation is complete, the icon will show in the upper right corner of your browser. Now To open the cookie manager, click on the image.
To import cookies, open the cookie manager and click the import button. A wizard with white space can now be seen. Copy and paste the hotstar premium account cookies you just grabbed.
Now press the submit or green tick buttons to complete the process. When you open Hotstar, you'll notice that you've logged into a premium account.