I use Nextgen Reader on my Windows 8.1 Pro (Update 1) desktop and on my Windows Phone 8.1 (release 8.10.12393.890) Lumia 620 phone.
I bought the App today from the desktop. If I check on the store I see the App as installed:
If I check on windowsphone.com I see the App as already owned:
But if I check the App on the phone I still can press the button buy:
Usually when I buy an App the buy button is changed in the share button:
The App is an universal app, so it should follow the rule: buy once and run on multiple devices (Windows or Windows Phone).
I don't want to try to press the buy button on the phone because I don't want to risk to be charged twice for the same App and have to ask assistance for a refund.
Can someone please explain me if this behavior is normal? Thanks in advance.