I purchased my new iPad in February 2021, it came with a free subscription to Apple TV.. when is my free period up

You can find the renewal date in the subscription settings on any of your Apple devices.

See your subscriptions overview - Apple

or Settings﹥[Your name]﹥Subscriptions﹥

One year from the day you activated the trial period, which I assume you have done. If you didn't, it's now too late to do so.