use the open kernel driver, which is MIT/GPL and thus cannot impose usage restrictions.
it's worth noting that "NVIDIA software stack" is an imprecise term. the driver is the part that has the datacenter usage term, and the open-kernel-driver bypasses that. the CUDA stack itself does not have the datacenter driver clause, the only caveat is that you can't run it on third-party hardware. So ZLUDA/GpuOcelot is still verboten, if you are using the CUDA libraries.
To what degree the GeForce software license is applicable even if you don't download the GeForce driver is debatable. It technically governs all software downloadable from nvidia.com including CUDA. The fact that you are only presented with the CUDA license while downloading might not stop Nvidia's lawyers. You might be safe as a consumer against EULAs without the ability to review and reject, but as a company, this might not slide.
it's worth noting that "NVIDIA software stack" is an imprecise term. the driver is the part that has the datacenter usage term, and the open-kernel-driver bypasses that. the CUDA stack itself does not have the datacenter driver clause, the only caveat is that you can't run it on third-party hardware. So ZLUDA/GpuOcelot is still verboten, if you are using the CUDA libraries.
https://docs.nvidia.com/cuda/eula/index.html