Tdameritrade rate limit applied to user, IP address or account.

I've created a neat non-delayed options simulator for myself and wanted to share it with my friends. I know some API's rate limit according to user or IP address but I am unsure of TDameritrade's rate limiting. They say they limit requests to 120 requests per minute for non commercial applications. I am fairly new to working with API's so apologies if this question has an obvious answer.