30 day trial

[Guest]

How is it possible to have the functionality as seen in many "try before you
buy" software apps that give you a free 30 day trial.

How could you mimic this in c#? I'm looking for theoretical approaches.

How is it able to count down 30 days.
....Session variable clears with every session, so
Application variable possibly?....
How do you count down time, use the system clock? But then the user can just
change the clock.

.... curious.

thanks, CR

 

[Marina]

It sounds like you are specifically looking for something for a web app.

Firstly, everything can be cracked. You can find a crack for pretty much
every major software product ever created if you look - including MS
products.

If you add an entry to the registry or something during installation to mark
the start time, then your app can check how many days it has been. Yes,
someone can change their clock. But then again, if they want your software
badly enough they will circumvent any other attempt you make to protect your
software. Additionally most people don't like having their clock set to the
same day forever, just to use some piece of software.

Additionally, who is the target of your software? If you are targeting
selling to companies, then those most likely are not going to try to get
your software for free anyway.

Also,applicaton variables are cleared every time the application restarts,
so that wouldn't work at all for you.

 

[Bob Powell [MVP]]

The user can change the clock so you can use a run count to put a limit on
how many times the control is run too.

The best way to do it is with a custom license provider.

You need to store a file or a registry setting with the date of first use
somewhere. Obviously this is not good to store as clear text so something
encrypted and base64 encoded is preferred.

If your time is worth money I would also reccommend that you look at a
commercial solution. Infralution provide a very reasonably priced system
that handles unique keys and 30 day trials.

--
Bob Powell [MVP]
Visual C#, System.Drawing

Ramuseco Limited .NET consulting
http://www.ramuseco.com

Find great Windows Forms articles in Windows Forms Tips and Tricks
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All new articles provide code in C# and VB.NET.
Subscribe to the RSS feeds provided and never miss a new article.

 

[Rodger Constandse]

Hi,

Infralutions provides a licensing system with a component that implements the
countdown mechanism using the registry <http://www.infralution.com>

If you need stronger protection, check out ExeShield <http://www.ExeShield.com>
which provides .NET protection for Win2000, WinXP, Win2003 but not for Win98/ME.

Best regards,

Rodger

Achieve Planner - Track your projects/tasks and schedule them in your calendar
<http://www.effexis.com/achieve/planner.htm>

Sequence Diagram Editor - Draw sequence diagrams faster
<http://www.SequenceDiagramEditor.com>

 

[Guest]

cheers everyone.

.... so its to do with the registry.....


thanks

 

[Guest]

Hi

Software locks can be cracked easily. You try it with registry or any other
method, If your customer is a computer geek then he can surely crack the code.

However if you use hardware locks, cracking such a mechanism needs quite a
bit of knowledge on system APIs and hardware. You can use memoHASP a hardware
lock provided by Alladin, (try entering HASP in google to find more) to count
the date or number of runs using timeHASP.

Software lock is not a good idea, unless you can manage a runtime
authentication using web, where ur software will check the date from your
website and will authorize everytime the date changes.

Regards

Amey

 

[LogicNP]

Instead of immersing yourself in these things, I would advice you to use a readymade licensing system ( see CryptoLicensing ) and focus on coding for your actual program. Saves a lot of time, money and headache