Sorry, but I think you miss the point. The link you point people to is all about people abusing the service and making unreasonable demands of the service. That doesn't seme to be the case with any of the people reporting problems here.

I know you track users by IP but I think ubuysa has it completely right...you incorrectly map IP addresses to 'licenses' and allocate each user some small pool of these licenses. So take my case as an occational recreation user. I maybe download grib data two dozen times per year...hardly unacceptable usage. But on travelling to Greece use mobile dial-up to collect weather data.

Of course each mobile connection on successive days is likely to be a new IP and you then incorrectly count that as a new license. I now see why my 'validation failed' appeared repeatedly. As other have pointed out, access via mobile device - GPRS/3G/sat-phone etc. is a pretty likely scenario for people sailing and so by definition moving about. It's very unlikely that people will have static IPs and so your 'licensing' model seems flawed.

Couild I suggest you instead consider some form of API key so the viewer submits a user-based key and it is this key track tracks a user, not their IP address which is bound to vary as they move from spot to spot.

.../Iain