Looking for cheap software that will allow my client to use my Photoshop mockup template

Hi. 

Are there any sites/apps in which my client can take my PSD files, where I created mockups for his custom products, and upload them and his designs to create product mockups? I know there are plenty of sites that allow you to choose a product mockup and upload your design but I am looking specifically for my clients to be a able to use the custom mockups I create for them in Photoshop, and add their designs and create images without having to have Photoshop. I thought Adobe Express did that but I read it is not built to work with mockup files or smart objects.  What do Graphic Designs give their clients, after creating Photoshop mockup templates, to allow them to use those templates to create images from their design images. 

Any help is appreciated!