Ah, you wanted this feature for the Event Calendar, got it!
This feature isn’t supported in our app, but we have this idea on the Wishlist. You can upvote it here - Option to put sponsors name/banner/address
As a workaround, you can add a sponsor logo to the Description field. For this, please open the Code Editor mode in the Description field and add this code there: <img src="Logo_Link"> :
Do not forget to replace Logo_Link with the link to your logo (it should be hosted somewhere) 