Smart Image Gallery search images in general. You should check copyright of images. If you click on the image, will be loaded the original page where the image is published.
The plugin inserts a shortcode in the article, so will be required remove the image's data from the shortcode, and save the article changes.
The external repositories like a Flickr, Picasa, Instagram, etc. include a big number of photos and images available for non-commercial purposes, furthermore, the external repositories reduce the bandwidth consumption from your web server.
This feature is only available for Flickr. Go to the settings page of plugin, and set the username for Flickr library
Note: The above is a safe process, the plugin's data and settings won't be lost during the process and will appear again after installed the pro version.
Alternative Installation Method:
The upgrade instructions are exactly the same instructions mentioned above but be sure to make a backup copy of your current files if you have made custom modifications to the files or translations since the files will be overwritten.
After upgrading the plugin remember to clear your browser cache.
The free version must be deleted before installing the pro version.
If you are upgrading the pro version to a new version you should also remove the previously installed version.
This is a safe step, the plugin's data and settings won't be lost during the process.
Another alternative is to overwrite the plugin files through a FTP connection. This is also a safe step.