There are two things to consider:
- Is the developer approved by Nintendo for access to Nintendo SDKs and tools?
- Does the developer have access to Nintendo Switch support for Defold as a community donor?
When it comes to 1) it is up to the Defold Foundation to only make the tools available to approved Nintendo developers. We will not give you tools access without Nintendo first approving you. And if access is revoked by Nintendo we must stop providing access. We will make an online license check when you build and fail builds if you are not a licensed developer. You can obviously use a cached build, hack the check etc but that is on you and you would be violating your agreement with Nintendo.
When it comes to 2) we will piggy back on the license check process and prevent you from receiving updates and performing builds if you no longer pay for access. We would also revoke access to the private forum category and download site for Nintendo Switch enabled versions of Defold. I guess you could hack your way around some of this but in general it will be hard for you to build for Nintendo Switch.
Please also keep in mind that $25/month is dirt cheap. Game Maker is $799 a year (Defold is $300). Not sure what it costs for Godot, but I’m guessing you pay more than $300 to get help porting your game. Unity and probably also Unreal are free but that is to be expected from game engine providers with almost unlimited funds.
Congratulations! 
