We highly discourage this practice, as we have found it is detrimental to sales.  However, if you wish, you may indicate that your product does have a special license.

You MUST indicate this in your description, you must select "Custom License" in the publisher.

In the Publisher, open the product and go to the Step 1 tab. Under the Product License section, enter or paste your Custom License text in the appropriate field, and save the product.

Again, if you have published 3D models with Custom Licenses, we encourage you to change the license types for these products to Standard or Editorial. Items with these license agreements are more attractive to customers and can garner you more sales than products with Custom Licenses.