Just make sure you keep your installation file for this program backed up
in a safe place you can always fine a a latter date if you need it along with
your key ...... then you have this version for life .
Now yes , latter on if a newer improved version is developed ( Upgraded )
there would be an upgrade price usually discounted .
This is common practice for most soft wares .( not all but most )
Here's 2 links to help you with questions you may have about the software .
1 - User Manual - https://www.stardock.com/products/multiplicity/v3/manual/
2 - FAQ - https://forums.stardock.com/486104/multiplicity-support-faq
Stardock Community Assistant