@suraj The data plans which Alpaca offers (ie the “Unlimited” plan) are completely separate offerings than general account access. The rate limit for the market data APIs (ie https://data.alpaca.markets) is separate than the rate limit to access one’s account via the trading APIs (ie https://api.alpaca.markets and https://paper-api.alpaca.markets). Those trading API rate limits are independant of any data plan you may choose and do not change.
The header responses can be fetched in different ways depending upon the SDK or method you use to make the API calls. For example, using Postman they appear in the ‘headers’ tab
Which language and/or SDK are you using?