How to fetch images from Pixabay

I am trying to fetch images from pixabay and show them in my blog post using JavaScript. My code is like below.

function imageSelect_blog(evt) {
            const imageURL = event.target.getAttribute('src');           
            $('#showuploadedimage').attr('src', imageURL);

            var xhttp = new XMLHttpRequest();   
            var url = "/admin/upload_pixabay_image.php";
            var data = { url : imageURL, id: "<?php echo $_GET['id']; ?>" };
            var params = JSON.stringify(data);

            xhttp.open("POST", url, true);
            xhttp.setRequestHeader("Content-type", "application/json");

            xhttp.send(params);
            bootstrapModal.hide();
          }

But after some days images are disappeared from Server.

Why is this happening ?