<<Resurfacing the information here from comments for broader community use >>
@Sendilkumar Thank you for reaching out with your query.
The pricing for Azure Application Insights is a Pay-As-You-Go model based on data volume ingested and optionally for longer data retention. Each Application Insights resource is charged as a separate service and contributes to the bill for your Azure subscription. Data volume is measured as the size of the uncompressed JSON data package that's received by Application Insights from your application. Data volume is measured in GB (10^9 bytes). There is no data volume charge for using the Live Metrics Stream.
First 5GB ingested per month is free , please feel free to use the below pricing calculator for estimations.
https://azure.microsoft.com/en-us/pricing/calculator/?service=monitor
Hope this information helps, please let us know if you have additional queries.