From the Sugru website:
Sugru has a shelf-life of 13 months from the day it's been manufactured. This means that the expiry date of Sugru depends on the day Sugru has been manufactured. We do our best to ship orders out to ensure customers have the longest amount of shelf-life left to use the product.
Tip: If you store Sugru in the fridge, the shelf-life triples!
You can find the specific expiry date of your products on the back of each single-use pack.