Ok, usually it would automatically show up at the end if it were regular text, but since you’re using a <h4> it causes everything else to start on the next line (sort of like a div container). A way to get around it is to add a float to it like this –
<h4 class="alignleft">Choose the Plan that best suits your needs</h4>
I added a class – class="alignleft"
which uses float left. Once you do that then it should cause the button to float up. Once you give that a try let me know.