As a side effect of running this benchmark for GPT-6.1 Sol, I measured that the Pro 100 subscription gives you $2.45-2.55 per 1% of weekly usage.
So, a $100/mo OpenAI subscription gives you ~$1,000 of API-equivalent tokens/mo. Not $2,000. Not $3,000.
I'm not sure whether this is something new, or if it always was like this. For Anthropic, I regularly spend $6K+ in API equivalent, as part of the $200/mo subscription.