Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Hello Lewisvdw
Hi, I'm Karl and will be happy to help you today.
A Microsoft (Office) 365 E3 license is a "business" subscription product licensed on a per user basis which includes a hosted Exchange account. There is no such thing as a one-time payment for an E3 license or any subscription based product for that matter. One-time payments only apply to "perpetual" licenses and the products would never be identified as '365.
The complete Microsoft description for an E3 license can be found at
Microsoft 365 E3 https://www.microsoft.com/en-us/microsoft-365/enterprise/e3?activetab=pivot:overviewtab
In short, whatever this site is trying to sell is not a legitimate product offering.