Did you give Adobe your credit card information?
This is an open forum, not Adobe support... You need Adobe support to cancel a subscription
-start here https://forums.adobe.com/thread/1703848
-or by telephone http://helpx.adobe.com/x-productkb/global/phone-support-orders.html
--and two links which may provide more details, if the above links don't help you
Trials have 30 days of shelf life, if you do not purchase it, it stops working automatically after 30 days.
What you are receiving is the prompt to purchase as only two days left.