You may be using another platform or chat company than OpenAI’s ChatGPT (chat.openai.com) or the OpenAI API.
There are many copycat phone apps, for example, that pretend and then extort.
ChatGPT is currently free at the basic level.
The API for software development is pay-per-use by the amount of data sent and received, but a new account may be granted a free trial credit in dollar amount.
Nothing is charged in terms of “messaging”. The only case that is remotely like that, using prepaid credits, is the Dall-E AI image creator.