Amazon has revealed that it added more than one million new Amazon Prime members in the third week of December alone as shoppers pushed to finish their Christmas shopping ahead of the big day yesterday. The growth in the service, which gives members free two-day shipping on a wide selection of items, led to Amazon’s busiest ever Prime shipping day. While that third-week growth of Prime might sound impressive, it could have potentially been even larger – Amazon said it had to limit new Prime signups during peak periods to ensure existing members were not affected by the surge. Amazon chief Jeff Bezos said the new members joined the “tens of millions” of Prime members that the company boasts overall. However, it’s worth noting that Amazon offers a free 30-day trial of the service, which users can cancel at any time to avoid paying beyond the free trial.