IPTV Smarters Pro allows you to add multiple Xtream Codes accounts. However, "Unlimited" generally refers to your subscription plan. Most standard IPTV subscriptions allow 1 or 2 connections (watching on one device at a time). An Unlimited plan allows you to use the same username/password on dozens of devices simultaneously (e.g., TV in the living room, tablet in the bedroom, phone on the bus).
Only if you are willing to learn. The "unlimited" aspect requires you to manage your own playlist, troubleshoot server errors, and understand the legal gray area.
Disclaimer: This article is for educational purposes only. Users are responsible for complying with their local copyright laws. Always respect intellectual property.