Hey, so here´s the problem.
Im triying to make some useful programs for some clases i took (for people who are beggining to see them). Im intending to charge something for them. The issue is that once ive transferred the file to one calculator, the owner will be able to transfer it to other calculators and so my program will only have some profit for the first couple of times i sell it. Then peoplel will be able to get it free by friends and stuff.
So is there a way to lock the document transfer? like with a password? or a way to make my calculator the only one able to transfer it? or something that keeps people from passing it on.

Excuse my english anyways. Thanks