Re: 30 days trial immune to set clock back in time?

Owen Jacobson <>
Sat, 20 Sep 2008 11:41:57 -0700 (PDT)
On Sep 20, 2:10 pm, Lew <> wrote:

Roedy Green wrote:

On Fri, 19 Sep 2008 04:53:43 -0700 (PDT), Tomer <>
wrote, quoted or indirectly quoted someone who said :

Can anyone guide me how can i create a 30 days trial to a software
that is immune to having set the clock back in time?

Icon Lover has a scheme that I wish more would implement.

It gives you a 30 day trial, but does not count days on which you
don't use the program.

1. use an atomic clock to find out the real time. See

2. give the user N uses of the program, over any length of time. They
would have to find where you hide the count.

3. Have the program send a query to a server on each trial use to see
if it ok to use it. You maintain the data on your server where it is
not discoverable or tamperable.


4. Do not provide time-limited or otherwise restricted copies of the soft=


  Require payment of the full license fee to receive the software at al=


That's extremely poor marketing. I'd instead frame that as:

4. Accept that some proportion of your userbase will subvert your
demo scheme rather than pay for the product.


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