My opinion is that it is not a good idea to submit your photographs to 'micropayment' sites eg: Dreamstime.  They prey on amateur photographers who don't know anything about the business.  They will sell your pics for a dollar, royalty free for anyone to use as many times as they wish, for any purpose they see fit.  

If you are represented by a reputable agency they will sell for a fair price a licensed copy, or a royalty free copy for an appropriate fee.

And every one said, 'If we only live,
We too will go to sea in a Sieve,---
To the hills of the Chankly Bore!'
Far and few, far and few, Are the lands where the Jumblies live;
Their heads are green, and their hands are blue, And they went to sea in a Sieve.

Edward Lear
http://www.nonsenselit.org/Lear/ns/jumblies.html