When i deploy my application i want to write to the registry to make
the application last about a month.I want the application to check
that date everytime it starts up then when the customer registers the
software i want the application to run like normal.If there is a
better way to do make a application timeout please any
suggestions.thanks
One of my favorite licensing schemes like this that I've seen (keeping in
mind I'm not a big fan of this sort of thing in the first place
) is
one in which a license key is encrypted with information that includes
whether there's an expiration date and if so when it is. The user enters
this key (or you could have them download it, or whatever) and then the
application decrypts the key to determine whether the application is still
licensed to run.
The reason I like it is that it's sophisticated enough to thwart naive
attacks like manually resetting a timestamp in the registry, and yet as
long as the user keeps a copy of the key somewhere (a good reason to keep
it short enough to write down) they will always be able to use their
software, and it's also weak enough that a user can work around a
licensing implementation error simply by resetting the clock on the
computer (it's important for any copy protection scheme to avoid
inconveniencing legitimate users, especially in ways that lock them out of
the application altogether).
The above scheme relies on you generating and transmitting the key to the
user, but you could implement a variation on the scheme in which the
program itself generates the key. This is less secure, since all the user
has to do is remove the application and any associated data in the
registry, but frankly if you've got a user who knows enough about
licensing implementations and the registry to hack that, they probably
know enough to get around any reasonably simple licensing implementation.
And since it's a bad idea to implement really obnoxious schemes that would
be more resistant to attack, because of the potential for inconveniencing
your legitimate users, you might as well accept the possibility of those
few more-sophisticated users getting around the scheme.
All that said, IMHO the best licensing scheme is none at all. Instead,
make sure you're providing some added value in the form of customer
support, regular updates, user forums, etc. that makes users want to pay
you for the product even if they can pirate it.
Pete
