Twitter Inc is resuming its Twitter Blue premium service, which gives users a blue verification badge with their name on it after it was suspended for weeks after some subscribers used the paid service to impersonate well-known accounts.

After several delays, the social network said in a blog post that Twitter Blue is now live. Users who pay $8 per month will receive a blue badge with a checkmark next to their profile picture and the ability to edit tweets, among other perks.

Twitter said it would take “several other steps to detect and prevent impersonation,” requiring users to attach valid phone numbers to their accounts. Users who change their username or photo will also lose the check mark “until Twitter reviews those changes.” “Accounts found to violate our rules may be suspended without refunds,” the blog wrote.

Before billionaire Elon Musk took the company private in late October, Twitter used blue badges to verify accounts to distinguish famous users or those who could be impersonated, including celebrities, musicians and reporters. But the process of obtaining verification is also unclear, and Musk criticised this as a “lord and peasant system.”

Twitter said it would also begin offering checkmarks in different colours, including a gold checkmark for businesses and a grey checkmark for political accounts. In a tweet late Monday, Musk said that Twitter Blue subscribers would also see half as many ads as regular users, adding that the company plans to sell subscriptions to an ad-free version of the service later next year.

Early attempts at paid verification systems led to widespread impersonation when users who purchased checkmarks changed their usernames to those of well-known brands and figures, including Musk. The verification process has been put on hold as the company tries to figure out how to fix the problem.

Musk also delivered a subtle blow to Apple as part of the Twitter Blue relaunch. The company will charge users $11 a month to compensate Apple for in-app purchases if they subscribe through Apple’s Twitter app for iOS. Musk has repeatedly complained about the fees, calling them “the de facto global internet tax.”

Users who don’t pay for Twitter Blue will lose their verification badges “within a few months,” Musk tweeted Monday, though similar claims have been made before.