Does a sub-theme needs the main theme enable? Just to clarified a doubt. 
But when creating a sub-theme, is it necessary to have the main theme enable ? 

Thanks
No, it is not necessary. You need to have your base theme installed, but you don't need to enable it: https://www.drupal.org/node/225125#comment-7716513

EDIT: Note that if you want to access the settings for your base theme, you will need to enable it, as noted by @MPD in a comment below.