Demo version is a cost free tool with certain limitation to examine the capability, functionality of the software. It is necessary to take trial of software before invest your money into it.
Yes it is necessary for Lotus Notes to Office 365 migration because without scanning the Lotus Notes platform none of the software is capable to read data and properties.
Demo version of the software contains all the functionality of full version but it has restriction on file migration. This version allows you to migrate first 25 items from each folder of Lotus Notes to Office 365.
Lotus Notes : 6.5/7.0/8.0/8.5/9.0
Microsoft Windows : 2000, 2003, 2008, XP, Vista, or Windows 7/8/8.1/10, 2008/2012 (32-bit & 64-bit)
MS Outlook : Outlook 2000, 2003, 2007, 2010, 2013, 2016 ( both 32 and 64 bit) versions.
Support : Windows 10/8.1/8/7 & all below Windows version
Hard Disk : 50 MB of free hard disk space
Processor : 1 GHz Processor (2.4 GHz is recommended)
RAM : 512 MB of RAM (1 GB is recommended)