https://www.youtube.com/watch?v=kMmiBvxqHJQ

Recharge your MTN SIM card with at least N50 or have at least N50 airtime on your MTN SIM card and dial ∗131∗25#. You will come across a menu asking if you would like the plan to auto-renew on expiry, this part is up to you to choose if you would like it to auto-renew by itself. After that part, if you are eligible, you will see the data on your phone and you can check your data balance by dialling ∗131∗4#.

On the other hand, if you get "you are not eligible for this offer message," it means that you will need to settle for another data plan on MTN or any other SIM card if you have any.

Just to save you the stress, you can simply check if you are eligible for the plan before you buy airtime on the SIM card by following the procedures above.

While some people are getting 200MB when they purchase the plan, some are getting 2x the amount of data making it 400MB for N50 instead of 200MB valid for the same 14 days. We don't know the criteria for having this but I think it has to be based on luck.

To conclude, the data is valid for 14 days and it can be accumulated i.e, you can get 1GB for N250 if you carry out the procedure 5 times and so on.