You might check why they say it's not a good idea. The reasons may not apply to your implementation. The one issue for which I'm aware is that "it can be spoofed". I'm sure that is true, but takes a pretty saavy person to a) know that's the method used to ID their computer and b) be able to spoof it so that they can still pirate your solution...
Of course there may be other very good reasons why it's a bad idea and I just may not be aware of them...
Im not really worried about anyone spoofing it, even if they do as soon as i get filemaker 12 ill use the get persistantID to lock it down, but what worries me about the nic address is that it seems that it can change for the user alot, if they change a pc componant or if they connect to the network differently, i guess it relative to the network card, though i dont know for sure, doesnt seem to be any source of info on the subject that is consistant.
What would the get persistantID script look like, i looked it up in the knowledge base but it does not give much on it or how to use it.
It's a get function: Get ( PersistantID )
Any time you need to know the "id" of the device currently accessing your database, you can use this function to check it.
If you built a table where you stored this value in a field, you could create a list of "approved ID's and then a start up script can check the value returned by this function against the values in this table and deny access to any device not on the list.
This can be an excellent supplement to any efforts to prevent unauthorized use of your solutions, but it can also complicate the technical support needs of your customers as you'll need to create the means to manage this part of your system. Consider what happens when a user buys a new computer and transfers your solution to this new machine--only to find that it doesn't work on the new machine as its ID isn't one of the ones one the 'approved list'.