I just got a reply from Spyderco. The basics are, they want to know who you are and what kind of knives you make. Apparently they dont want to just license anybody, but are seeking to protect their trademark and they do restrict the usage to custom makers who produce no more than 100 knives per year with the hole. Cost is indeed $50 per year. Sounds like reasonable request from Spydie, so I'll put together an application for them.
Trademark laws differ from the USA to EU (European Union). Having a Trademark in the USA doesn't mean it's valid worldwide. Getting a trademark worldwide is a costly undertaking and involves lawyers who specialize in such laws. I dont know if Spyderco's trademark is worldwide or not. I want to try and do the right thing in any case.
Ken, if you are in the USA, I think the short answer to your question is, yes, you need to either use a maker who is licensed by Spyderco or the maker you want to use must apply for a license from Spyderco. To simply use the trademarked hole without Spydies permision would be a violation of the trademark and could result in legal action against the maker. One must take into consideration, the practical situation of paying a lawyer to chase after things like that... I think Spyderco wants mainly to keep other manufacturers (domestic and foreign) of knives from using the hole - and I can certainly understand that too.