It's fairly well known that piracy of any sort, software or otherwise, is risky business for a number of reasons. On top of the legal implications, pirated software often comes from untrustworthy sources and can be full of all sorts of nasty surprises like malware, keyloggers and even trackers that the authorities can use to identify and locate a pirate. Despite these caveats, piracy runs rampant on Android, mainly due to how easy it is to download a cracked APK file or take a legitimate ripped APK and run it through one of the numerous cracking programs out there, leaving you with a perfectly working copy of paid software for free, or a copy of free software with no ads, as is the case here.
The particular app is Textra SMS, which has begun detecting pirated copies and issuing warnings to users. If a user is found to have a pirated copy of the app installed on their device, they are warned that the app is pirated and that a legitimate version must be installed from Google Play within three days. The warning says that Textra considers piracy a "serious matter" and that they will not hesitate to report "repeated violations". Although Textra is a free app with fairly unobtrusive ads, many users pirate it anyway, leading to a good chunk of lost revenue.
Speaking on the matter to TorrentFreak, Max of Delicious, Inc., Textra's development house, said that the warning may scare pirates, but it's also in place to let unaware users who would otherwise have downloaded a legitimate version know what's going on, such as those who may be a bit technically challenged and handed their friend their phone to install the app. Speaking on consequences for noncompliant users, Max said, "Legally there are a whole raft of options all the way from DMCA takedown requests to civil proceedings. It's not a big issue for us, but on occasions we try our best to encourage users to 'do the right thing' that's all,". He went on to talk about the risks in piracy outside of the legal spectrum, saying in conclusion, "Why would you do that!?"