Credit on your Vodafone Card is active always for a period of 7 months after last charging or after buying, if you haven't charged.
The initial Extra Credit is valid for 45 days from SIM activation and you can use it for Vodafone services (you cannot pay for third party services such as SMS tickets).
After your credit expires, you still have a three-month period to renew your Vodafone Card.
If you do not top up your credit even after 10 months from the last top up or SIM activation, your phone number will be automatically cancelled due to inactivity.