I've bought Photoshop CC 2015 throught Creative Cloud before running the trial version in my computer. After installing the Creative Cloud, the box with remaining days still apears. How can I proceed?

confirm that your account shows the subscription(s) you expect (and that the adobe id used in the next step is the correct one) by logging in here and checking your subscription status, https://www.adobe.com/account.html

then, if it is current, sign out and then back in to your cc desktop application using the same adobe id used with the above link:  http://helpx.adobe.com/creative-cloud/kb/sign-in-out-creative-cloud-desktop-app.html

if that fails, Creative Cloud Help | Creative Cloud Applications Revert To Trial Mode Updating To CC 2015