We sell products under 3 licensing models.
Personal usage license – the product can be downloaded for single user and used for single or multiple end products. Fonts, Add-Ons (actions, brushes, etc), and other installable items may only be installed on a single computer, but can be used in multiple projects. When used as part of a new work, there’s no limit to the number of copies of the new work that can be distributed so long as the copies are not offered for sale
Commercial license– the products downloaded can be used for single user and used both for personal and commercial products. Fonts, Add-Ons (actions, brushes, etc), and other installable items may only be installed on a single computer, but can be used in multiple projects. You can include the items as a part of the derivative products with a link to item vendor. (For example you can use the font for the logo and provide font source file and a link to font owner). The derivative product must be larger that the original product and have sufficient visual difference.(For example you can Bootstrap theme as a basis for your WordPress theme, but the resulting product must visually differ from original Bootstrap theme)