William Shatner, Monica Lewinsky and other prolific Twitter commentators — some household names, others little-known journalists — could soon be losing the blue check marks that helped verify their identity on the social media platform.

They could get the marks back by paying up to $11 a month. But some longtime users, including 92-year-old Star Trek legend Shatner, have baulked at buying the premium service championed by Twitter’s billionaire owner and chief executive Elon Musk.

After months of delay, Musk is gleefully promising that Saturday is the deadline for celebrities, journalists and others who had been verified for free to pony up or lose their legacy status.

“It will be glorious,” he tweeted on Monday, in response to a Twitter user who noted that Saturday is also April Fools’ Day.

After buying Twitter for $44bn in October, Musk has been trying to boost the struggling platform’s revenue by pushing more people to pay for a premium subscription. But his move also reflects his assertion that the blue verification marks have become an undeserved or “corrupt” status symbol for elite personalities and news reporters.

Along with verifying celebrities, one of Twitter’s main reasons to mark profiles with a free blue check mark starting about 14 years ago was to verify politicians, activists and people who suddenly find themselves in the news, as well as little-known journalists at small publications around the globe, as an extra tool to curb misinformation coming from accounts that are impersonating people.

‘Pay for something you gave me for free’

Lewinsky tweeted a screenshot on Sunday of all the people impersonating her, including at least one who appears to have paid for a blue check mark. She asked, “what universe is this fair to people who can suffer consequences for being impersonated? a lie travels half way around the world before truth even gets out the door.”

Shatner, known for his irreverent humour, also tagged Musk with a complaint about the promised changes.

“I’ve been here for 15 years giving my (clock emoji) & witty thoughts all for bupkis,” he wrote. “Now you’re telling me that I have to pay for something you gave me for free?”

Musk responded that there should not be a different standard for celebrities. “It’s more about treating everyone equally,” Musk tweeted.

For now, those who still have the blue check but apparently haven’t paid the premium fee — a group that includes Beyoncé, Stephen King, Barack and Michelle Obama, Taylor Swift, Tucker Carlson, Drake and Musk himself — have messages appended to their profile saying it is a “legacy verified account. It may or may not be notable.”

But while “the attention is reasonably on celebrities because of our culture,” the bigger concern for open government advocate Alex Howard, director of the Digital Democracy Project, is that impersonators could more easily spread rumours and conspiracies that could move markets or harm democracies around the world.

“The reason verification exists on this platform was not simply to designate people as notable or authorities, but to prevent impersonation,” Howard said.

One of Musk’s first product moves after taking over Twitter was to launch a service granting blue checks to anyone willing to pay $8 monthly. But it was quickly inundated by impostor accounts, including those impersonating Nintendo, pharmaceutical company Eli Lilly and Musk’s businesses Tesla and SpaceX, so Twitter had to temporarily suspend the service days after its launch.

The relaunched service costs $8 a month for web users and $11 a month for iPhone and iPad users. Subscribers are supposed to see fewer ads, be able to post longer videos and have their tweets featured more prominently.