For years, Amazon has been charging an annual fee of $79 for Amazon Prime membership, which includes free two-day shipping on many items and access to a library of streaming movies and TV shows at no extra cost. For people who take advantage of both aspects of the service, it’s a pretty good deal at under $7/month, but is that all about to change?

In a conference call to discuss its fourth quarter earnings report on Thursday, Amazon admitted that it’s considering — not definitely doing it, but considering — raising the annual fee for Prime by twenty to forty dollars.

Amazon says there are “tens of millions” of Prime members around the world, growth that has likely been encouraged by increased use of tablets and other wireless devices that can stream Amazon Prime videos.

In its earnings report, the e-tailer says it increased the size of its Prime video library from 33,000 titles to 40,000 in December. It’s also recently begun getting into original programming with the launch of two shows, Alpha House and Betas.

It’s possible the additional costs of content acquisition and creation may be causing Amazon to look at that $79 and dream of a bigger number. Maybe the company will have different tiers of Prime service for people who want the video plan and those who just want the free shipping benefits? We don’t know as Amazon isn’t saying.

Amazon has made changes to Prime that some say make it less worthwhile. First, it began labeling some items as “add-on” items that did not count toward the minimum purchase total to qualify for free shipping. Then it raised that minimum from $25 to $35. For customers who had used Prime for many, smaller-dollar purchases and didn’t watch any of the streaming video selections, these changes took away a lot of the value for the program.

Amazon considering $20 to $40 price hike for Prime service in US [TheVerge]

Want more consumer news? Visit our parent organization, Consumer Reports, for the latest on scams, recalls, and other consumer issues.