Query about this plugin?

Good afternoon all,

I’m looking to purchase the Pro version of this plugin, but first I would like to confirm it will do what I wish for my blog before I do so.

I have just updated my WordPress blog theme and it uses the Featured Images for the thumbnails.

As my previous theme did not use Featured Images, I have 10,000+ blog posts that have no Featured Image.

They do all have an image at the top of the article that I link to, however, those links are from images uploaded to my server from a different section of my website (basically they are not in the Media section of my blog).

If I purchase the Pro version of this plugin, would it be able to automatically add the Featured Image for all 10,000+ blog posts from the “first image in the content”?

And if so, just to confirm does it matter if the “first images in the content” are not in my WordPress Media uploads?

I look forward to a reply.

Thank you.