As far as I could tell, having had it a while, there is no enforcement. Not that I used it on more than 5 or 6 machines. Paragon works mostly on honesty, it seems. I have installed and reinstalled some of their other tools and never had any block or query.
When the new version came out I automatically received an email and a new code for the new version since i was in my 12 month updates period. Didn't have to ask or go on the site to get it or anything