Do I need to buy Premium/Pro version again on a new device?
No, the premium upgrade or pro purchase is tied to your Google account. Just use the same account on Google Play on the new device, and your previous purchase will be recognized. Buying Premium in-app purchase in FolderSync doesn't give access to FolderSync Pro but unlocks the free version to be identical to the pro version in every way.
How do I get a refund?
We can offer refund up to 72 hours after purchase or if your premium upgrade is not recognized and you want to cancel it or buy the pro version instead. We can also offer refund if you want to transfer license to new Google account, but some old purchases may for various reasons not be refundable in the Google Play console so we cannot guarantee this.
Please see this link for further details: https://goo.gl/forms/e21sKHBkVXaqBnE92
Why can I not get Pro version when I have purchased premium upgrade?
The premium upgrade in the free version of FolderSync unlocks it to be identical to FolderSync Pro, but it doesn't enable download of pro version as its a different app on Google Play and the Pro version can only be downloaded if bought directly. If you have issues getting your premium purchase recognoized and want to cancel buy pro version instead, please request a refund.
Why can I download the free version, but not be able to buy the pro version?
There can be many reasons for this. Some countries like China are not supported by Goggle Play. Another reason can be that the device is not valid, because it doesn't follow Google guidelines. Note that FolderSync is not restricted from any devices or countries by our doing. There are several steps you can take to try to remedy the situation.
Try using market enabler or similar tools: https://market.android.com/details?id=ch.racic.android.marketenabler&feature=search_result
For people with MIUI rom (and possible others with custom roms): http://miuiandroid.com/forums/showthread.php?7779-Protected-apps-in-the-market-shown-as-not-compatible
Problems with your purchase on Google Play?
Sadly any problems with Google Play is outside our control. You will have to ask Google for support. If you can't download a purchased app, try again a little later or try restarting your device, then it usually works. A few users simply can't purchase apps, and they continually get "Internal market error". If you think you have accidentally purchased the app twice, then please check the billing statements. One of them will probably say cancelled and that no charge has been performed, so there is no need to contact support for a refund.