ok well justs think of it logically.

1. load application
2. check current user (i.e. login)
3. find if user has expired (from database or other source that holds signup date
4. if it has expired disable / hide form and show signup for full trial

basically you will need someway of storing the users details about when they first used the app / installed it.

Best way i can see of doing this is via a database of users (as wouldnt you be using a database to login if this was the case anyway ?)

i dont really know what you want all these sections if you dont know how to perform them will be easily found by googling. if you need anymore help just pb.

hello fungs,

Thanks for your reply.
Yes, i also thought the same way as you have mentioned. But it is not possible!
Actually, the complete query is

First, the username and password should not be strored in the database, but in some file or something like that so that no other person can locate where it is stored and placed.

Second, when the software started on the user computer then he/she will enter a date for the first time and that date field will be stored in some file (not in database) and the date will be compared with the number of days to be used. So that after completion of the days the software stops working and the login name and password get expired for the user.
Now, i am just looking for the point from where to start.
I have searched on google too, but of no help.
So, i posted my query here. If anyone can help me i will really appreciate that.

Thank You.

Hello Sayen, This is not much problematic.

See, when the apllication runs in a clients computer for the first time, try to write a file in some directory, if little deep it will normaly will be unoticed by a common user.

Store in it the date first started this program. ofcourse, if the data is cripted it is more good.

In your program before loading the particular form cheack the file iwhether it is created or not.

if created read the cripted date, decript it ,subtract that date from now(), if > 30 exit sub else create the file, store the Now() in it, endif

One problem is there. If somebody knows it, he will keep on backdating the computer and your form will be ever visible.
This, you have to trade of.

Happy programming!

Hello Manoharan,

Thanks for your reply.
I got the point, but can you tell me, do i need to use some special type of file or can i go with notepad.
Should i store the username and password in the same way (if yes), then in the same file or use some different.
One thing more can you tell me how can i encrypt the data.

Thanks again.

you can use any old file even make one up to meet your needs. the best solution would to make an encryption yourself. this could be a really simple one or as complex as you wish to make it. But storing the data shouldnt be too much of a problem. Just make sure you know how you have saved it and how to read from it. A the end of the day all applications are not HACKER PROOF some are just harder to beat than others.

i actually have a encryption class i use in .net which is a pretty easy one. it just converts a string to its hex value perhaps something as simple as this would meet your requirments. there are plenty of tutorials out there that would show you how to do this.

and that gave me an idea why not share what ive done to all the lovely people out there. encryption http://www.daniweb.com/code/showsnippet.php?codeid=726

Thanks Fungs,

I will try this and let you know.