Why is there an expiry date on the sim package?

[Eler]

Is this just  like a sell by date or will the sim actually stop working after this date?

[_MrR_ · Accepted solution]

Not exactly...

If the sim pack hasn't been activated by that date then yes, that pack will expire. The number (which isn't live as it hasn't been activated) would then be re-used elsewhere. 

If, before the expiry date, the sim has been activated and is then live then the expiry date is no longer applicable.

From that point on, the standard expiry rules relating to chargeable activity and top-ups apply.