Your subscription for Fences 3 still exists obviously, and will work on your machine until Microsoft changes your OS enough to make Fences 3 unusable.
Stardock has continued to develop and improve Fences, and now sells Fences 4, no longer Fences 3.
https://www.stardock.com/products/fences/
At the bottom of that link, in green, is a discount for owners upgrading to Fences 4.
More on your topic here:
https://forums.stardock.com/512318/page/1/#3851475