OpenAI's free version of ChatGPT has a new look: Users who don't pay to upgrade will now see ads when using the artificial intelligence platform.   The company  said  on Monday that it is testing ads with ChatGPT users in the U.S. with "free" and "go" subscription tiers. The "Go" plan costs $8 monthly.  OpenAI said in January that it would start piloting ads  as the company looks for ways to further monetize its widely used chatbot, along with subscription fees for premium users. Customers who