Can these two stocks make you a millionaire? If you hold on to them long enough, it's possible. Sure, they aren't cheap, but these companies have steadily increased revenue and offer the promise of more in the coming years.

If retirement is years down the road for you, you will have plenty of time to watch sales -- and share prices -- multiply.

A man holds a laptop in front of a wall of computerized data.

Image source: Getty Images.

Amazon.com

Amazon.com (NASDAQ:AMZN) is trading at a record high, but the shares have further to go well into the future. Even as the coronavirus pandemic has hurt revenue at most companies, the online retail giant said first-quarter net sales increased 26% to $75.5 billion. The company has hired more than 175,000 workers over the past few weeks to handle the increase in demand.

Though the outbreak will be temporary, Amazon's sales growth won't stop when customers stop stockpiling essential goods. The retailer has a history of strong sales growth, with more than a decade of steady gains. Amazon predicts net sales will climb between 18% and 28% in the second quarter.

The diversity of Amazon's businesses also makes me confident about its future, from cloud computing to grocery. Amazon Web Services (AWS) is a significant part of the picture. The cloud computing business is a strong profit driver for Amazon, with AWS' first-quarter operating income making up 76% of the company's $4 billion in total operating income. And AWS posted a 33% increase in quarterly sales.

Amazon's leadership in grocery is a plus as more and more consumers turn to online shopping. Online grocery sales grew 15% last year, according to a Brick Meets Click analysis. Last year, Amazon began offering free two-hour grocery delivery to Prime members in certain regions. In other areas, same-day or one-day delivery is available. In the recent earnings call, Amazon said online grocery is growing, and the company increased delivery order capacity by more than 60% to handle demand due to the COVID-19 outbreak.

Amazon shares aren't cheap. They are trading at 113 times trailing-12-month earnings, close to their highest ever by that measure. But that doesn't mean gains are over, especially if you have the ability to sit back and wait a few years.

Netflix

As we might have expected, Netflix (NASDAQ:NFLX) saw a huge boost in subscribers as people around the world stayed home these past several weeks. The company reported a gain of nearly 23% to 15.77 million net additions in the first quarter as more and more viewers had more time for entertainment.

It's possible that some of those newer members will end their subscriptions after returning to their normal routines, and it's unlikely that Netflix will see gains of the same extent on a regular basis. That said, if history is any guide, we still can be optimistic about Netflix attracting more and more subscribers into the future. Netflix has steadily increased subscriber numbers since 2015. Now, the company predicts an increase of more than 25% in the second quarter, with the addition of 7.5 million new subscribers.

With competition such as Apple TV or Disney+, how can Netflix keep up this kind of pace? Through its original content. The company said in December that its original content was the most popular of all new releases offered through the service last year.

Netflix said it intends to release shows and films as planned in the second quarter. The coronavirus outbreak led to a production halt, but Netflix is compensating through the acquisition of titles to assure the continuity of fresh content.

Some say Netflix shares have gotten too expensive; they are trading close to an all-time high. And Wall Street only expects 3.6% upside from here this year. But for an investor looking for growth over a period of years, the Netflix story is far from over.