Accessing Loopy Pro via TestFlight is, I believe, the best experience as it allows you to select a particular build for install, so you can try the latest versions, safe in the knowledge that you can always downgrade, which is a regrettable impossibility with the App Store. If you would prefer to simply get a promo code, however, feel free to ask me for that.
Install the TestFlight app on your iOS device and tap the button below to install Loopy Pro.
In the TestFlight version of LP, you will still see a “Purchase” screen, but it’s just a sandbox – that is, pretend money. When you go to “buy” the full version, you will see in the purchase screen that you will not be charged. No “payments” in the TestFlight build will actually charge you.
By default, you’ll have access to the latest release build. You can also select older builds which correspond to the publicly-released versions: select these in the TestFlight app.
If you’d like to help with the beta testing effort, feel free to request access to beta versions instead.
If, in the future, you decide you’d like to purchase Loopy Pro after all, you can do so the usual way, on the App Store; the App Store version will replace the TestFlight build (but just in case something goes awry, you could back up your important projects first).