I can't answer for custom modules but in DNN we use some licensing code we purchased a licence for -it allows us to verify a user's details (name and licence), and generate a unique key based on the configuration of the installation where the module is installed (e.g. the machine name, the OS version, the IIS AppID etc.). This value is then written to the database, and is used to verify that a licence is valid and still active and running on the machine that was activated. Evoq uses an install level licensing model so this works well for us, but I notice many modules use portal level options e.g. a licence can apply to 1 portal, or a number of portals or be an "enterprise" license for an entire site or machine. I'm sure there are generic licensing options out there (with example asp.net integration code), but in many cases I imagine people put together custom systems. Note: we (store.dnnsoftware.com) have in the past considered offering a centralised licensing system that module developers could easily integrate to, I believe this is still on the list for future consideration and I hope we end up delivering it as it would be very useful for those module developers who don't have the time to roll their own.

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