Creating (and maintaining) a great app can require a ton of work, so we're happy to compensate developers for all that effort by shelling over a few bucks for their content in the Play Store. But while many app-makers rely on this income stream, a new bug that's popped up in a recent Play Store update threatens to toss a wrench in the works, interfering with how apps can verify paid licenses.
This License Verification Library issue first appeared in the Play Store v10.7.17 update (and is still present in the v10.7.18 release), and concerns a problem with the ILicensingService used by apps to verify the presence of license data on a user's device. These licenses can help prevent unscrupulous users from attempting to sideload apps they never paid for, or even buying an app, extracting its APK, returning it, and then trying to reinstall it.
As a result of the bug, apps aren't able to call the checkLicense() method used to verify license status. It would be bad enough if that info were just being reported to apps incorrectly, but some apps don't seem to know what to do when they can't access this data at all, and consequently freeze up or experience other unintended behavior.
This puts developers in a quite uncomfortable position. They can ask that their users remain on Play Store v10.6 or earlier, but that could prove difficult to enforce on a broad scale. Alternatively, since ILicensingService can't be used to check whether an app's been properly paid for and licensed or not, devs can configure their apps to default to one of two states: either assuming that every user is licensed, or that none of them are. On one hand you risk encouraging piracy, while on the other you deprive users who've supported you of what they've paid for.
Clearly, a better and more permanent solution is needed. Over the weekend the bug was reported on the Google Play Core Library issue tracker, and this afternoon a Google employee finally responded that the problem is under investigation. We're hopeful that means that a fix is on the way soon.
Google has begun distribution of a new Play Store release that appears to fully restore license verification functionality. Play Store v10.7.19 is available now, and multiple reports confirm that it resolves this recently-introduced bug.