Amazon’s Prime subscription offering is unique — it offers free shipping, streaming videos and access to a Kindle library, all for $79 a year.We like how Prime keeps adding services without increasing the price — instead they’re able to go for volume by adding more subscribers. In fact, Amazon’s total net service sales was more than $2 billion for Q2 of this year, compared with $1.3 billion during the same period last year. (Amazon’s Q2 report defines net service sales as those sales for digital subscription services, affiliate commissions,  third-party seller fees, and non-retail activities; it’s unclear what percentage of these sales are from Prime subscriptions alone.)Prime also routinely offers a trial, and recently has been advertising it on their homepage, taking up prime real estate for selected users (I didn’t see the Prime trial offering on my Amazon homepage, but a co-worker did, leading us to suspect Amazon is targeting either expired users or prospects that qualify in some other way).

The personal letter in a well-designed format is a nice touch. However, we usually don’t recommend a one-month trial — people tend to forget they’ve signed up for a trial after 7-14 days, and that could increase your cancel rate. But assuming a behemoth eCommerce site like Amazon has tested their trial length, we suspect this is the optimal length for their services and products.Here’s the copy of the letter (to inspire and steal from!):

Dear Customers,In 2005, we launched a program called Amazon Prime. For just $79 a year, Prime members got unlimited Free Two-Day Shipping on a million different products. Prime was an outstanding offer and many people joined the program.Today, seven years later, Prime is even better. You now get unlimited Free Two-Day Shipping on 15 million products. Prime also now gives you unlimited instant streaming of over 22,000 movies and TV episodes, as well as the Kindle Owners’ Lending Library, an exclusive service where Kindle owners can borrow from a library of over 180,000 books for free, with no due dates. And despite all this investment, Prime remains just $79 a year.Amazon PrimeMillions of people are already members. In fact, we now ship more items with Prime Free Two-Day Shipping than with Free Super Saver Shipping. If you haven’t tried Prime yet, you can start a one-month free trial today. We think it’s the best bargain in the history of shopping, and we hope you do too.Happy shopping, happy watching, and happy reading,Jeff BezosFounder & CEO