My 7.1 surround pro seemed to be revoked and I don't get it

I bought 7.1 surround pro app about 5 years ago and I've been enjoying using it ever since. But after I installed Version 1.1.75, it does not work any more. It says "7/1 Surround Sound is not enabled on this account. Please use a valid Activation Code to unlock this feature" I totally don't get it. First, I bought the app here on razor store. Second, When I install the older version of the app, it still works (with greyed out devices list though - this is a different matter I think) Could you please check why it is like that? Thank you