I've bought the product by credit card but when I try to start Adobe Photoshop the system asks for a seria number and it wasn't included in the e-mail of confirmation

Rodrigo.09 what version of Photoshop are you trying to open?

If you are facing difficulty authenticating Photoshop CC or Photoshop CC 2014 please see Sign in, activation, or connection errors | CC, CS6, CS5.5 - http://helpx.adobe.com/x-productkb/policy-pricing/activation-network-issues.html for information on how to resolve the connection error preventing authentication.