Claro...........it works like this,
if you get a 100 pesos card it will last for a month, after that period if you dont get another card your phone get into parcial suspension which last for 3 months
it gives you a total of 4 months before u lost your number
Since u will be out for longer try to get someone to buy you an electronic card(just giving your phone number they can recharge it) at the end of the 4 months so you can keep your number for another 4 months