Paguei e não funcionou

See also here: https://community.adobe.com/t5/acrobat-reader-mobile-discussions/cancel-subscription-check-if-you-are-eligible-for-a-refund/td-p/13342390

Where did you buy the application? If you bought via the Google Play Store or the Apple App store, refunds need to be asked with them. If you bought directly from Adobe and you cancel during the first 14 days of your paid subscription, you will be refunded automatically.