Steve,

IMHO, setting the security fuse on the uC is the only way.
Any other way, ie download a licence, can be easily duplicated.
I ask myself... I want to rip off Steve's code... well, he's just sending
some kind of validation number... then I'll just check out the validation
number and reuse the same one on all my Clones of Steves hard work.

Another way, but it requires you to be set up with a tech line to provide
the access codes. Every time the unit powers up, have it produce a
random number which is sent to you, then you give a validation number
back based on whatever encryption you want. Hmmm... might work,
but the key to this is producing a random number that can not ever
be "fixed". Even if this were possible, I'd still be able to disassemble
your code and crack it *IF* it was time effective. Otherwise, I'd just write my own code.

Steve, I only believe the most secure way is by using code protection security fuses... and even that is not so secure!... I've heard of experts
being able to circumvent those and get at your code. How they do it is beyond me and the scope of this forum.

Josh.