Independent software vendors who participate in Microsoft’s ISV Royalty program should be aware of the criteria:
One thing to be hyper aware of in terms of compliance is the Microsoft requirement to incorporate all license terms into your customer agreements. This means if your customers are using your licensing improperly, you are in danger of being out of compliance. Be sure to very clearly state their usage rights!
This seems like a lot to ask – but the ISV licensing program can save you up to 50% on licensing costs. Microsoft provides a lot of information on the benefits of the ISV Royalty Program.