NEW YORK (TheStreet) -- Amazon (AMZN - Get Report) has steadily been growing its cloud business, and its annual conference last week showed off just how far it's come.

At the Amazon Web Services re:Invent conference, Andy Jassy, the SVP of AWS, shared some important milestones. Just six months after Amazon first decided to break out its financials separately, AWS is a $7.3 billion business -- up 81% year-over-year -- and now has more than one million active enterprise customers.

Meaning that AWS has already surpassed analysts' expectations for full-year revenue. In July, Cowen and Co. predicted that AWS would bring in $7.1 billion in 2015.

Cowen surveyed more than 200 companies that use public cloud providers, and AWS came in first place in terms of share of budgets, average annual spending and expected spending growth, and was a close second to Microsoft's (MSFT - Get Report) Azure in terms of overall usage.

Respondents on average spent $124,000 last year on AWS, twice the amount of money as those that use Alphabet/Google's (GOOG - Get Report) (GOOGL - Get Report) Cloud Platform and IBM's (IBM - Get Report) Soft Layer. And the average for AWS is expected to rise, according to Cowen, which estimates that spending on AWS by existing customers is expected to increase 43% in 2015 and 21% in 2016, while spending on cloud services from other vendors is expected to stay relatively flat.

"We continue to be impressed with AWS' focus on innovation, scale, and usage," JMP Securities analyst Ronald V. Josey wrote in a research note on Thursday. "Overall, coming out of AWS re:Invent this year, we are incrementally positive on shares of Amazon given the opportunity around AWS coupled with its continued strong retail operations."

Even as Amazon reaches these new milestones, it continues to add new features to its AWS offering, showing its commitment to grow the business even more. Over the two-day re:Invent conference, AWS announced a vast amount of product releases and updates, including an Internet of Things cloud platform, a new business intelligence tool, hardware that can store data and be sent to AWS, and a new security tool, to name a few.

"As it is our understanding is that AWS' clients are increasingly less sensitive on price and despite the lack of punitive contractual terms elect to stay on the platform for the breadth and depth of services, the accelerating pace of these products and features remains an encouraging development," Credit Suisse analyst Stephen Ju wrote in a note on Friday.

Still, there's no denying that Amazon is battling a large number of cloud services providers to get a larger piece of the pie. Microsoft, IBM, Google, and Salesforce (CRM - Get Report) are all pushing their own cloud services.

"Like in the e-commerce space, Amazon's strength is in highly transactional markets," said James Keller, Executive Partner at advisory firm Bulger Partners. "The enterprise space, with its high-touch requirements, will be a challenge for Amazon, and partnerships like the Rackspace relationship will be critical. Don't be surprised to see an acquisition with strong pro services capabilities."

Despite these challenges, though, Amazon is certainly flexing its cloud muscles and signalling that it has a serious interest in beating all the other players. And many analysts are optimistic about its opportunity.

"We walked away from AWS re:Invent increasingly bullish on this segment," Oppenheimer analyst Jason Helfstein wrote in a research note on Friday. "We also met with several AWS systems integrators, who reiterated our view that Amazon is by far leading the Cloud revolution. While there are bottlenecks with any new technology, we see pace of innovation from Amazon as outstanding."