I know this is an old question, but I thought I'd comment on it rather than opening a new one.
Isn't a license for "Support and upgrades for 12 months"? Paying for a license and installing the package from nuget is no different than me paying for a license and downloading the .zip file from your website. When the version isn't supported by my license, it doesn't work... if you implement a license file.
I just upgraded the license for another nuget package, Mail.dll. The difference between that and your product is that they supply a license file which includes the company name, number of licenses and expiry date. That needs to be included with the application when it's deployed, otherwise the mail functionality includes a "please register this product" disclaimer in the subject line.
You don't have the concept of a license file. If you did, you could deploy to Nuget. This would offer two benefits that I can see:
1. It is much easier to make security fixes available to your customers. It is immediately apparent to anyone using nuget packages that a new version is available. You can even mark unsupported / vulnerable versions as deprecated.
2. A secondary benefit, if you were to think about it, is that when a new version comes out and a customer installs the new package, they could get some sort of message that their license is out of date at that very moment. This form of automatic and _immediate_ notification could only have an increase on your renewals, from my viewpoint. It would require implementing some sort of license file as I described for Mail.dll above.
