The flexible paywall that The Boston Globe introduced for its subscription website about a year and a half ago has slowly gotten a little less flexible. Fewer Globe stories are available on the paper’s free Boston.com site, and restrictions have been placed on social sharing.

The reason, according to Globe spokeswoman Ellen Clegg, is that the paper’s executives are still trying to figure out how to get paid online journalism right in a world awash in free news.

“The core of our two-brand strategy,” she told me by email, “involves trying to find the optimal balance between a free, ad-supported model and a premium, consumer-supported model.”

The restrictions were brought home to me recently when I learned that the paper had started limiting social media sharing to only two free links a month — a serious limit on someone like me, who regularly shares links on my blog, on Facebook and on Twitter. As a subscriber, I can share as many links as I like, of course. But non-subscribers can only click on two before getting a message that they cannot pass go.

So let’s run down the changes, shall we?

First, those social-media links. Clegg says that when BostonGlobe.com went live in the fall of 2011, social sharing was limited to five links per month. If so, it wasn’t well publicized. I’ve gone back and looked at some of the coverage, including my own for the Lab and the Globe’s own FAQ, and can find no mention of a monthly cap.

In any case, Clegg says that in December 2012, that number was cut to two links a month from search and social media — “per device, and per browser.” In other words, eight a month if you want to juggle among Chrome, Safari, Firefox and Internet Explorer (but who wants to do that?), and more if you move back and forth among other screens. “Email sharing,” she adds, “is unlimited.”

Second, when BostonGlobe.com debuted, the editors selected five stories a day that would also run on the free Boston.com site. Most sports stories ran on Boston.com as well. Last April, the number of free news stories was cut from five to four, and some additional sports content was moved behind the paywall.

“This is part of an effort to continually experiment, test and analyze how our readers engage with us digitally,” Clegg says. “We have been trying to find the right balance between the free-sharing culture of the Internet and paid access to premium Globe content. We believe that we can only arrive at that balance through experimentation.”

How well is it working? The Globe’s digital subscription base has risen, but slowly. Currently, Clegg says, the Globe has about 50,000 paid digital subscribers — but that doesn’t mean 50,000 people paying directly for a digital subscription. It’s a figure that includes digital-only subscribers; Sunday-only print subscribers (I’m one of them), who automatically get seven-day digital access; and seven-day print subscribers who access BostonGlobe.com at least once a week.

That’s how digital subscriptions are counted by the Alliance for Audited Media (formerly the Audit Bureau of Circulations), and it’s a pretty expansive definition. As I’ve written before, about half of those counted as Globe digital subscribers get the paper delivered to their doorstep all seven days.

So is the decision by Globe executives to tighten the paywall smart or dumb? It’s hard to say. From the beginning, the idea behind the paid BostonGlobe.com site was to find a way to get regular readers to pay without turning away occasional readers and without hurting the free, advertiser-supported (and just-redesigned) Boston.com site. (Here is how Globe publisher Christopher Mayer explained it to me shortly after plans to build the paywall were announced in the fall of 2010.) Today, Clegg says, Boston.com attracts about 6 million unique visitors a month. Another 1.5 million uniques a month visit BostonGlobe.com, mainly as a result of the site’s free-access features.

I know that since I learned about the two-links-per-month limit, I’ve been looking for the equivalent content in Boston.com’s news blogs or elsewhere. I tend to shy away from BostonHerald.com unless I’m writing specifically about the Herald, since much of its content moves into the paper’s paid archives after two weeks. But there are plenty of other sources of free local news, even if it’s not always of the same quality as the Globe’s.

I’m inclined to cut the Globe some slack as Mayer, editor Brian McGrory and company grope their way into the future. But the new rules have already nudged me away from Globe content, and I’m a paying customer. That can’t be a good thing.

Photo by Scott LaPierre used under a Creative Commons license.