Whenever you engage someone to create intellectual property (IP) for you, make sure you put an agreement in black & white. It will help you evidence and protect your right to ownership of the IP.
A legal document to assign (transfer) ownership of intellectual property is often called an IP Assignment Agreement or a Deed of Assignment of Intellectual Property.
A deed is considered more formal than an agreement and should be used where no payment or other consideration is made for the assignment. That is because a "deed" is more likely to be enforceable.
If you don't have evidence that you own the intellectual property you use in your business (such as website copy, photographs, software, film scripts and customer lists) the original creator may limit how you can use it or, worse still, sue you for using it.
It makes it harder to sell your business if you can't prove you own the intangible items such as IP.
So when you pay creators for their work, make sure you have them sign over the IP to you.