What makes a template premium
Standard designs share one set of sections and differ in style. Premium designs are built individually, which is why they can do things a shared layout cannot, like scroll-driven scenes or a page that plays like a film. They can also show a picture for each of your projects.
Worth paying for?
If your field is visual, or you want your page to be remembered, it can be. If your work speaks for itself in plain words, a free design may serve you just as well. Trying a premium design costs nothing, so look at it with your own details before you decide.
If you stop paying, your page stays up on the closest free design and your choice is remembered, so your link keeps working.
