Speakout airtime lasts 365days, other company's airtime only last a month usually.
If you do not use all your airtime in a full year, and do not add anymore airtime to it before the expiry date, then yes, it will expire and you will lose it.
If you don't use it, then what you can do, right before it expires, you can buy additional airtime, and then the expiry date will be extended another 365 days.
This is one of the biggest difference between monthly plans and "prepaid" or "pay-as-you-go" plans. With monthly plans, it's use it or lose it at the end of the month.
With prepaid plans like SO and PC, any unused minutes are carried forward as long as you add more airtime (any amount) before the current minutes expire. And SO is far superior to the likes of Telus and Fido because the minutes are good for 365 days (PC is good for 180 or 365 days but that's still better).
I have another question kind of related to this thread.
Do the minutes/time "stack" on top of each other? For instance, I have a Tracfone I use when I go to the USA.
If I enter a year card, then it is good for a year. If I enter another year card a week later, then the expiry date is pushed up another year.
So, right now if I buy a $25 SO pin, it lasts a year, and calling *777 will tell me my expiry date lasts a year from now. If I buy another $25 a month later, will it put another year on from the last expiry date, giving me two years?
If I take last post as an example, does that mean if I have $25 loaded in Jun 2008 and added another $25 in May 2009 and not single minute used since first fund loaded nearly a year ago would be added to May fund i.e. 25+25 and expiry for whole $50 dollar minutes would be May 2010?