Android demo for Free App change to Paid App

Here we show the sample demo for Free App and Paid App For this we need to develop two Application one for free and another for paid

we should add all the functionality in the free App and we can lock the some functionality those we need to enable in Paid version

Paid version App act as key to open the functionality in free App

Steps

1. Create free App with all functions and lock function those we want
2. Create the paid App , it must invisible to the user after installing, so we not use intent filter in manifest
3. Use the same signed key for both App for generating signed APK
4. For opening the locked functionality in free App we check "package name of the paid App and signature"
5. If the paid App is installed in the device then check the signature , it is used for avoid hacking and there is a chance for the same package name for the App
6. If both condition same we get the results as true , so we can enable the lock functionality

Code for check the paid app package name and signature

``` java
	private Boolean isProInstalled(Context context) {
	// TODO Auto-generated method stub
	String proPackage = "com.polus.binil.apppro";
	  // get the package manager
	  
	  final PackageManager pm = context.getPackageManager()
	  ;
	  // get a list of installed packages
	  List<PackageInfo> list = pm.getInstalledPackages(PackageManager.GET_DISABLED_COMPONENTS);
	  
	  // let's iterate through the list
	  Iterator<PackageInfo> i = list.iterator();
	  
	  while(i.hasNext()) {
	    PackageInfo p = i.next();
	    // check if proPackage is in the list AND whether that package is signed
	    //  with the same signature as THIS package
		
	    if((p.packageName.equals(proPackage)) &&
	       (pm.checkSignatures(context.getPackageName(), p.packageName) == PackageManager.SIGNATURE_MATCH))
	      return true;
	  }
	  return false;
}