Combine paid theme (regular license) with my own theme

I purchased a ThemeForest WooCommerce theme (regular license), but it contains a lot of things I don’t need. So I was thinking to start from a self-made theme and copy the parts that I need from the purchased theme? In other words, can I use the design and some assets (images and fonts) from the paid theme to use in my own (nearly similar) theme. Is this allowed with a regular license?

Assuming that it is for one private/client website then it is - you couldnot do that and then try to sell the end result here or on any other marketplaces

Yes, I am only building a webshop for a client and do not want to sell the end product on any marketplace. Thanks for your quick answer!