If you have over 100 credits, you probably have a 25-assets/month annual subscription. And yes, it is a free trial, but if you do not cancel at the end of the trial, you have a full-fledged for pay subscription for a whole year. And the terms & conditions were mailed to you at the very moment you took your subscription, not mentioning the fact that you clicked the “I have read and agree” button for the terms and conditions. When you cancel the subscription now, you will need to pay half of the remaining due as an early termination fee.
All this said, I would suggest contacting Adobe customer care and to negotiate your way out of this contract. I don't know if there is any refund in for you, as according to the conditions, the option window for a refund closed 14 days after the start of the paid subscription.
Adobe customer care can be contacted by beginning a secure chat session at https://helpx.adobe.com/contact.html?rghtup=autoOpen. Pop-up blockers need to be disabled, you need to accept cookies! If the chat window fails to open, or is non-responsive, use a different device and/or browser to start the interaction.
For support via Twitter:
https://twitter.com/AdobeCare
(see also here: https://community.adobe.com/t5/creative-cloud-services/how-to-contact-adobe-support/td-p/11875703 or here
https://community.adobe.com/t5/account-payment-plan/how-to-contact-adobe-support/td-p/11843852)
Important: Adobe does NOT contact you unsolicited by e-mail or direct message. If you get contacted by direct message from a person, claiming to be an Adobe employee, look at that profile and look, if they bear the “Adobe Employee” marking under their name. Adobe support does not use Skype to give you support.
If in doubt, ask the forum.