Google has removed several shady apps that charge users huge amounts if they fail to cancel a free trial in time, and simply uninstall the app or allow it to lapse.
Security experts at Sophos discovered apps including basic QR code readers, compasses and calculators that didn't contain any malicious code, but took advantage of app trial periods to fleece users.
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According to Google's terms and conditions, you should cancel any premium app before uninstalling it to avoid being billed in future. Most developers are quite lenient and take the fact that you've removed the app from your phone as meaning you want to cancel, but not all are so generous.
That's usually not a huge problem, as the typical premium Android app only costs a pocketful of change, but those identified by Sophos billed users up to $240 (about £200, AU$360) if they failed to tap 'Cancel' in time.
To add insult to injury, most of the apps in question were extremely basic, making it all the more likely that users would uninstall them quickly, or forget about them entirely.
Avoid being scammed
Sophos provided Google with a list of 15 apps engaging in the shady practice, 14 of which were subsequently removed from the Play Store, but the security researchers have since found even more – some of which have been downloaded millions of times.
To avoid falling victim to such a 'fleeceware' scam, be wary of any app that asks you to provide payment information before beginning a free trial, and check for fine print stating exactly how much the subscription costs per year. It's also wise to check recent reviews before installing new apps, as people who have been tricked often leave warnings for others.