ASSIST is Russian electronic payments provider, founded in 1998. Company start coincided with Russian eCommerce market developing, and electronic payments industry launching.
Please find more information about how to install plugins here.
The plugin is provided absolutely for free and includes source code. Find the project Github repository here.
UPDATE: nopCommerce team doesn't plan to upgrade this plugin to the latest version. Our community is more than welcome to continue development of the plugin. Please feel free to use our source code.