Recharge zain prepaid line for 25kd you get one year validity. The validity of the line will only increase when you recharge your balance with an amount that has number of validity days higher than your current validity.
Example 1: If your current line validity is until 31/12/2017 and on 31/03/2017, you recharged with KD1 which gives up to 7 validity days, the expiry date of your line will remain the same.
Example 2: If your current line validity is until 31/12/2017 and on 31/03/2017, you recharged with KD25, which gives up to 365 validity days, your line validity will extend to 31/03/2018.
Recharging your balance after the expiry date will allow you to reactivate your line from the temporary disconnection, which can lead to a permanent termination and losing the ownership of your line.