As of May 7, 2017, Free Data for Life is no longer available for new activations. If you signed up for FDFL on or before May 6, 2017, you can keep it with your current tablet as long as you own and use your tablet with T-Mobile.
Free Data for Life gave you 200 MB of free 4G LTE data every 30 days if you continued to own and use the eligible device with T-Mobile.
To keep Free Data for Life postpaid customers need to maintain an On Demand data plan at a minimum to continue to receive the offer ($0/month for voice customers after $10 line credit). Prepaid customers need to maintain an activated account.