Can't start more than 2 encoding session on GRID K1

According to , GRID card is not limited to 2 encode sessions per system. I have two GRID K1 card in my host, but i can’t to start more than 2 encoding sessions. I try to start parallel 3 instances of nvenc sample from nvenc_4.0.0_linux_sdk and for one of it I have message:

File: src/CNVEncoder.cpp, Line: 1872, nvEncOpenEncodeSessionEx() returned with error 10
Note: GUID key may be invalid or incorrect. Recommend to upgrade your drivers and obtain a new key
NVENC error at src/CNVEncoder.cpp:1874 code=10(NVENC indicates that the API call failed because it was unable to allocate enough memory to perform the requested operation.) "nvStatus"

On this host I have: Debuan 7, CUDA 7, NVIDIA driver v. 346.59, nvenc_4.0.0_linux_sdk.
Do I need to install some additional software or get special license key for running more than two encoding sessions?

What is the GUID being passed into nvEncOpenEncodeSessionEx()? What are the parameters that you are passing into NVENC for encoding?