On 10/30/2012 1:48 AM, scott wrote:
>> A lot of developers write magic numbers to the registry so that when
>> your trial period ends, uninstalling and reinstalling the application
>> will not reset your trial period.
>
> Is this method really used? There are programs to record all
> reads/writes to the registry, so you really can delete all the keys
> created. Or you just restore a backup of the registry to start the trial
> again. I suspect they are a bit more cunning than this.
>
Yeah, it is. There are very few programs out that track changes though, 
and they are usually "security" type things, like one called scoty (or 
something like that), which watch dog they thing, so look for odd 
changes, like something adding a new startup program some place (it 
catches everything doing that, so even legit stuff gives a pop-up, which 
can be interesting...) Other cases may be hidden files, in odd places, 
etc. One of the kind of interesting ones is a "give away of the day" 
thing, which doesn't actually demo, its installer actually registers it, 
within the 24 hours of the give away, and flat refuses to install it as 
a working application, if the server says "no".

But, in general, adding some sort of flag to the registry, with a date, 
or the like, is the simplest solution. So, in principle, if you knew 
what changed, you could undo it.

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