Why not buy the full version which has three differences.
1) It doesn't have Demo Version wrote on the title screen.
2) It will allow you to save any number machines made. Without this the program is useless.
3) It comes with printed instructions.
When you buy the full version you will become a registered user and will be entitled to free upgrades and you will receive information on future products.
You can buy the full version with or without a site licence.
A single user version costs £3 and a site licence allowing as many copies as you want is £5