challenging problem. highly expert knowledge needed.

[alidabiri]

hi all,
i work for a small custom software company specializing in accounting software.
our team has been developing an accounting package for a business firm. this firm markets this package starting with the trial version that lasts for 30 days. we know that some customers may use the trial version that expires in 30 days and then un-install it, and re-install it and use it for another 30 days. my question is: is there anyway to determine if a particular pc has ever installed this package, even if they have un-installed it before installation?

 

[Peddant]

my question is: is there anyway to determine if a particular pc has ever installed this package, even if they have un-installed it before installation?

Yes,you leave a hidden key(s) in the registry.That`s how shareware has done it since time began.

Links - One and Two and Three

 

[Samstoned]

new stuff uses internet logon and gets the machine ID
only way to bypass is complete rebuild of machine with diff parts
ID is held in the class area of registery
when user runs program the key is sent back to your server and bang denied

 

[alidabiri]

thanks peddant, and sam.
peddant, is that legal? i mean to leave a "key" or anything on a user's computer? i thought sony got in trouble for doing that - leaving a small program on a dvd player's memory or something to prevent copying.

 

[Nodsu]

Virtually all programs leave their registry entries and even some files behind after uninstallation. It is either the laziness of the programmers, the shortcomings of the (un)installer, or a feature.

Sometimes it is actually good to get all your settings and such back after you have uninstalled and reinstalled a program. And often it is not possible to tell, whether a file should be removed or not.. Would you like MS Office to delete all your documents after you uninstall it?

There is a huge difference between some leftover files or data and a malicious program BTW.

 

[Tedster]

commonly known as orphaned files......

 

[Peddant]

i thought sony got in trouble for doing that - leaving a small program on a dvd player's memory or something to prevent copying.

Sony got into trouble for taking the concept to extremes,by virtually taking over the OS.More info HERE