[TedCarron]

I have been developing a piece of software for a while now and I want to try and sell it thru the very familiar 'free trial period' method via download sites.

My question is what is the best way to implement the fixed trial bit? I guess the idea is to store the installation date somewhere on the target machine either in a registry key or a small file somewhere.

Does any one have any refinements on this strategy or comments they would like to make on the subject in general?

[gregoryH]

TedCarron, on 28 May, 2007 - 01:05 AM, said:

I have been developing a piece of software for a while now and I want to try and sell it thru the very familiar 'free trial period' method via download sites.

My question is what is the best way to implement the fixed trial bit? I guess the idea is to store the installation date somewhere on the target machine either in a registry key or a small file somewhere.

Does any one have any refinements on this strategy or comments they would like to make on the subject in general?

HI

The method can be circumvented unless you use some types of encrytpion algorithm on the registry stored data.

I know because I have edited a registry to extend the use of a product beyond 30 days.

The strategy should:

• encrypt date information
  
• check date settings against last date run

to assist you in managing the users (especially ones like me)

There is a gent here in Sydney who is a programming security expert, Malcom Smith. He has written components for both Borland and I believe MS VC++ which do this very job.

I am bordering on the rules of this site as this is commercially available, but he does have some free stuff on his web site www.mjfreelancing.com as well.

Have a surf, see if his stuff is suitable.

[alpha02]

To make things simple, a registry key is the way to go. It must be encrypted in a decryptable way. Invent your own cryptography algorythm, this way not everyone can figure out what the encryption means. Do NOT give the key a name that describes the program, or simply give a number as the key's name.