ChatGPT offers a free plan that’s available to all users indefinitely....

https://rowanscoolperspective.iamarrows.com/is-there-a-standard-1-month-chatgpt-plus-free-trial

ChatGPT offers a free plan that’s available to all users indefinitely. Occasionally, targeted promotions provide free trials for the ChatGPT Plus subscription, which may require a card and auto-renew when the trial ends