I have recently started getting this message. The issue seems to be the app is linking to a secondary Google Play store account on my device and not the one Join is logged in as, the one that has purchased an unlock. If I click on of the unlock options in the app it shows the purchase dialog as the secondary account. I cleared Join data, switched accounts in Join and Google play store, didnt work. Is there anything else I can try beyond removing the secondary Google account temporarily?