A "portable" version means the software is repackaged with a crack (modified executable that bypasses license checks). Dangers include:
The next day, Elias took his laptop to a local repair shop. The technician, a young man named Leo who happened to be a fellow rail enthusiast, shook his head. "Those 'free license' sites are a minefield, Elias. Especially the 'portable' ones—they're the perfect wrapper for viruses." anyrail license key free portable
The safest way to use AnyRail is through its official channels: A "portable" version means the software is repackaged