Please follow this procedure if Smart Launcher can’t verify your license and if you are using more than a Google account on your device.
– Uninstall Smart Launcher, if you want you can perform a backup to avoid losing your configuration;
– Using a computer open this page https://play.google.com/s
– Click on “Install” in the web page, then wait the install process to finish on your device.
– After the installation check if Smart Launcher recognized your license. If it doesn’t a reboot could be necessary.
Since the issue causing this problem is related to how Google Play Store handles purchases in a multi-account environment, this procedure could help even if you’re experiencing the same problem with another app. Let us if the procedure helped you in our community.