If you are upgrading from ESave Free, remove it from your project first before installing ESave Pro.
You can find the latest version of ESave Pro in the asset store with this link.
Installation Steps:
Get ESave from the asset store.
Open your Unity project, go into Window > Package Manager, switch to My Assets from the packages dropdown at the top-left, and then type ESave in the search bar.
Download and import the package. You may be prompted to install package manager dependencies. Click Install/Upgrade.