Advanced Access Manager (aka AAM) is free WordPress plugin that you can download from the official WordPress Repository however some feature may require to purchase our premium extensions.
You can either download it from the official WordPress repository or install from your website backend area on Plugins->Add New page.
We strongly encourage first to take time to learn about WordPress access management. It is most likely a lot of things you will be able to accomplish with the free version. You will be absolutely sure when premium extension is needed because it will be explicitely articulated either on the AAM page or in the extension's description.