For next prerelease we have something new.
We add three new classes: AppReceiptMBS, AppReceiptIAPMBS and AppReceiptVerificatorMBS.
The AppReceiptMBS class allows you to load the receipt from within your own app or from a given file. You can query identifier, app versions, various dates like purchase date or expiration date. Using the AppReceiptIAPMBS class we provide an array of the in-app purchases. For each in-app purchase you can query details like product identifier, purchase or cancellation dates, quantity or the transaction identifier.
Our AppReceiptVerificatorMBS class can verify if app receipt is valid. Either you pass in a receipt, bundle identifier and app version to check if some receipt file is valid for a given app. Or you just ask if the application's own receipt is valid.
We hope this helps Xojo developers using the Mac App Store. As we also have the whole StoreKit framework covered from Apple, you can use the MBS Plugins for a complete In-App Purchase solution.
Plugin will be available soon as part of pr8 or if you like to try it on the weekend, I could email you a copy.