Code sample for Paypal subscription with ASP.NET

Is there a code sample or a really good article that talks about integrating Paypal subscriptions with a ASP.NET website?

I'd like to provide a 30 day trial period during which they are开发者_运维百科 not charged (even if they cancel). If they choose to continue, they are charged every month. The paypal documentation is not very helpful and I've yet to come across a code sample that implements this.

Any help is appreciated. Thanks

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Disclosure: this is a blog posting I put out:

http://www.codersbarn.com/post/2008/07/10/ASPNET-PayPal-Subscriptions-IPN.aspx

From memory, if you check the PayPal parameters, there is a way to set up trial period.