How to detect that an app is linked to Play Store or not? Previously, Android Market didn't show Uninstall button for apps which aren't installed using it. So, this button was a nice identifier of linking status. Now, Play Store displays the button for every app.

Problem starts here: Titanium Backup started to show some of my purchased apps as unlinked from Play Store. It was unexpected.. Something had broke it. I could re-link apps using Titanium Backup, but I needed confirmation to avoid more problems. Well, I checked it using other apps like  App Manager of ROM Toolbox Pro. Interestingly, all such backup apps are displaying different linking status. So, I am screwed up.

I want to discover linking status without any help of third-party apps.
Go to https://play.google.com/store/account, with a regular desktop. Then click on the tab 'orders', you shall find there all the apps you downloaded via Google Play.

After clicking Install or Installed button, you'll get pop-up having device list. If app is already installed in a device with linked status, device would be inactive to send install signal. It can be used as identifier.