The Mac app store is asking me to buy the app again
All updates to 2Do so far have been free. There are no paid updates to worry about and so if you're certain you purchased 2Do earlier and are seeing a "Buy" button instead of "Install" or "Update", please try the following:
1) Try compressing the app in /Applications (right click, click Compress) and then moving the compressed zip file to a secure location. Then, delete 2Do.app under /Applications. Spotlight for 2Do.app and delete any other copy found. Now launch the app store again and see if that picks it up.
2) Try restarting your mac and then logging out and logging back into the Mac app store.
3) You probably changed your credit card recently or updated it without updating records in iTunes. A good way to test for this is to try and download a free app from the Mac app store. It may prompt you then to update and verify your credit card. Perform steps 1 and 2 after doing this. Alternatively, follow this link for advice on how to update your payment information.
3) If you feel this is still an error, developers have zero control over the whole iTunes purchase process. Billing, refunds, authorizations, returns etc are all handled by iTunes. The best place to report a problem is to iTunes itself for that order.
4) If you've recently moved to a new country, as standard practice, iTunes nullifies all previous purchases tied to that country. You will have to take this up with iTunes support.
5) Lastly, if all of the above does not apply, proceed by clicking on the Buy button (ensure you're logging into the same account as the one you used to purchase 2Do with) and proceed with any prompts that come up. At the last step it may recognise your previous purchase and inform you of it, at which point you won't be charged and it'll download for free. In case you are charged the retail amount of the app, please request for a refund from iTunes immediately. NOTE: If this is the first time you've verified your credit card with iTunes, iTunes will still charge you a dollar or less for the purpose of verifying your account. This is NOT the same as paying for the app. In any case, if you have concerns about the whole process, please report it to iTunes.
P.S: We frequently get people writing to us saying "iTunes support staff said they don't deal with payments and have asked to contact the developer instead" or "Sorry, the developer chose to charge you for the update, you need to contact them" - this is untrue. We have not charged for any of our updates, nor do we deal with the licensing process. Apple charges developers 33% of all transactions for the very purpose of handling this on their behalf. Unfortunately, you will need to insist that they provide you with the required support you deserve.