android - How to share my service only to users who purchased my application in Google Play? -

i publish android app in google play application uses service created myself, sake of example let's it's java rest service hosted somewhere. provide service authentication client able invoke methods on application purchased on google play.

i solution compatible if user changes device , downloads application on other device using same android market username.

it great if user didn't have provide kind of credentials every time launches client, in other words solution transparent end user.

if want nobody not use app able access webservice, simple solution webservice requires specific parameter app sends every request.

let's webservice requires parameter "key" "secretkey". let app add parameter every request, webservice not ignore request. if tries access webservice, won't provide correct key-value pair , not response.

if, of course, want make sure user has paid app, , not gotten apk somewhere else, not work.