Data Retention, Data Visualization

Can someone tell me about the number of days your variables historical data will be retained in blynk IoT Cloud also explain about Data Visualization ?
in all of the plans?

This forum only covers the free (developer) version of Blynk.

As far as the free version is concerned, I have data on the cloud servers that goes back three years. It can be viewed in SuperChart, but only the last 10 days or so can be downloaded via CSV export, or reports.

If you set-up a local server with raw data storage enabled and sufficient storage space available then you have direct access to the SQL database where the data is stored, so you can report and visualise it any way you wish.