I was charged 26.99 and I never used it since I bought it month ago. I never know how to use it for edit PDF

Or, to edit you must download and install and use the Acrobat Pro app. Stop using the free Reader.

Here are the subscription terms. If you have questions about how to edit a PDF, please ask in a new thread.

http://www.adobe.com/legal/subscription-terms.html

Acrobat products and Document Cloud

Annual contract, paid monthly
Service begins as soon as your initial payment is processed. You’ll be charged the rate stated at the time of purchase, plus applicable taxes (such as value added tax when the stated rate doesn’t include VAT), every month for the duration of your annual contract. If the applicable VAT rate (or other included tax or duty) changes during your one-year term, the tax-inclusive price will adjust accordingly. Your contract will renew automatically, on your annual renewal date, until you cancel. Renewal rates are subject to change, but we’ll always notify you beforehand. If you cancel within 14 days of your order, you’ll be fully refunded. Should you cancel after 14 days, you’ll be charged 50% of your remaining contract obligation and your service will continue until the end of that month’s billing period. Cancellations can be made any time by visiting your Manage Account page or by contacting Customer Support in your region.

Annual contract, prepaid
Service begins as soon as your payment is processed. You’ll be charged the annual rate stated at the time of purchase as one lump sum, plus applicable taxes. Your contract will renew automatically, on your annual renewal date, until you cancel. Renewal rates are subject to change, but we’ll always notify you beforehand. If you cancel within 14 days of your order, you’ll be fully refunded. Should you cancel after 14 days, your payment is non-refundable and your service will continue until the end of your contracted term. Cancellations can be made any time by visiting your Manage Account page or by contacting Customer Support in your region.

To Cancel https://helpx.adobe.com/creative-cloud/help/cancel-membership.html

-or reply #1 in https://forums.adobe.com/thread/2023066 - includes Mon-Fri Chat link