Since I recommend this to every Hivean here, I am not saying you have to source your images, I suggest it to eliminate any undue issues with anyone who goes after people who do not source. That is strictly up to you. I would sincerely recommend that you start sourcing those from this point forward though as it displays to the community that you have the sufficient permissions to use that photo, since your post is monetized.
Here is a post I made on it for simple sourcing:
@jamerussell/easy-and-correct-minimal-sourcing