New authors often think that once they've purchased a book cover, they own the cover and are therefore free to do whatever they need with the cover. While this is a common misconception, I'm afraid this is almost never the case in the cover art world for a number of reasons.
And that's why instead of purchasing the copyright to the art when you buy a cover or a piece of art, you're often purchasing a license to use the art in particular ways.
Which ways? Well, that depends on the designer.
For example, if you purchase a premade e-book cover from me, you're purchasing a license to sell an unlimited number of e-books and to use the e-book cover to promote that book. If you want to use that cover to sell non-book commercial merchandise (e.g. t-shirts or mugs with the cover art on it), you have to purchase an additional license (the commercial merchandise license add-on) to be able to do that.
Note that even when you purchase licenses from me, I still retain certain rights (e.g. the right to show the cover to promote my business, the right to tell others I created the cover) and the copyright for the design overall. The licenses you purchase and the rights I retain are all clearly described in the terms and conditions you agree to when you purchase from the Shop or have custom work done by me.
Simple. If you purchase from another designer, you'd read their contract to determine what rights they give you.
As much as I hate legalese and completely understand the frustration and boredom just the word 'contract' triggers, I always push authors to read the contract. This is a business after all. In the end, each designer is different, and the legal agreement between the two of you is all that will matter for your specific situation.
I also recommend that you read this summary here. It's by far the most concise and detailed summary of book copyright and licensing I've come across. It corrects the common misconception on the internet that book covers are automatically work for hire. (They're not.) And it's quick to read and easy to understand. Do yourself a favor, save yourself a lot of potential future regrets, and take the 5 minutes to read it. You'll be far more comfortable navigating the business part of book covers if you do.
This varies from designer to designer, but in case it helps you gain a frame of reference for what I've found to be common among the many indie designers I know, this is what I see most frequently, especially with book covers created through photomanipulation (a common technique used to make a lot of book covers):
Now, that's just a very common default. For some designers, that's the end of it. They will not sell you the right to sell commercial merchandise with the cover art and they will not sell you the right to modify the art in any way. (Or if they will, it will cost a lot.)
For other designers, it's the starting point. You can purchase an additional commercial merchandise license that will allow you to sell mugs, t-shirts, etc. with the cover art (assuming you purchase the extended licenses for any stock photos used), or you can buy the equivalent of a modification license that lets you make adjustments to the cover art yourself for specific reasons or if you follow certain directions. Some designers let you purchase one, but not the other. Some require attribution on the copyright page. Others merely request it. A lot of these details really are designer specific. But this at least gives you an idea of what is a common default.
If you're ever unsure what licenses you're purchasing, ask the designer specifically for written clarification and please, please, please READ the contract. If the contract doesn't include information about what you can and can't do with the cover by the time you have to sign it (or tick a checkbox on a website saying that you have read and agree to abide by the terms - very common for premade cover purchases), don't purchase from that designer.
To protect yourself and to avoid accidentally breaking the law, you need to know (in writing in the contract) exactly which license(s) you have purchased and what you're legally allowed to do with the art. Great cover art is a must to sell your books today, and great art at a great price is even better. But remember, this is one of the biggest purchases you'll make for your book's marketing. The only way to avoid regrets is to know what you can do with it before you purchase.
Want to learn more? Sign up to my e-mail list here. In addition to getting early access to new premade covers before anyone else and periodic exclusive discounts, you’ll also get concise, detailed information about what makes a book cover good at its job and how to ensure the book cover you get is one that will put your book into the hands of the right readers.