It's free to sign up, store a limited amount of pictures and use them in posts here, but you still get the ads, unless you pay for an account. See the picture below for current pricing and details. I have a free account with a lot of pictures and have only used about half of my limit. I see the ads, and had to turn off AdBlocker to use the site.
I find that I see fewer ads when I choose the 'slideshow' option to view the pics, and close any ads that pop up right away, even before they fully load sometimes.