The Government can simply ban the use of that software without a license set at a future date (i.e. 1/1/2017). New Regulation -> Future Date -> Ex post facto c

The Government can simply ban the use of that software without a license set at a future date (i.e. 1/1/2017). New Regulation -> Future Date -> Ex post facto claims don't happen. That is the process my original comment intended to imply.