You've been experimenting with translating very large amount of text and hit the free trial limit. The actual paid plan's limit is much higher than that of the trial, and it should be enough for most use cases.
If what you did was not an experiment with the add-on but rather a real-life work, please let me know what kind of work it is and how much text (in words or characters) you are anticipating to be translating throughout a month.
You can email me at the address in the from field of this message.
Thank you.