Hi, robynkop!
Thanks for reaching out to Microsoft Community and posting your inquiry regarding the Surface Pro 4 devices you plan to purchase. We understand you want to use the Neurofeedback system loaded onto the device. As for the product end of support, there's no information released yet about this. You may bookmark this page to get updates on the Microsoft Lifecycle Policy. Even if the device is out-of-warranty, you can still get in touch with Microsoft Support when you need assistance. If it involves replacement, agents will base it on the original start date of the device's warranty. If it is already out-of-warranty and the device needs service/exchange, a fee is needed and you can see more information on this page on How to get service for Surface.
We hope this helps you out.
Kind regards,
Janette_Z