I have no ethical problem with DRM.  I'm simply coming from a
mathematical / techinical perspective.

Some of the greatest minds have tried working on it, and the conclusion
is uaninimous: you can make it more annoying or cumbersome for someone
to duplicate or modify the software, but you can't make it impossible.

Again, you can put whatever limitations you want into your interpreter
- but I can always modify the binary (google IDA Pro) or create my own.