It's been a while since I've had to edit photos and I can't remember what program I used but you could create a water mark and it would apply it to all your photos if you set it that way, might want to check under your settings/options.
Lightroom.
There's a guy on an AR15 forum that always integrates his watermark in his pics (like I did in mine) so it doesn't ruin them but you know it's his.