Gemini offers a free tier that handles day-to-day writing and brainstorming...

https://blogfreely.net/samuel-wang09/gemini-subscription-renewal-date-how-to-track-your-spend-and-manage-your-plan

Gemini offers a free tier that handles day-to-day writing and brainstorming with ease. If you are a power user or professional needing deeper capabilities, the Google One AI Premium plan costs $19.99 per month