Many folks are experiencing issues with the Mac App Store when updating from the iPad version.  It's a bug on Apple's end.

A couple things to know and try :
 
- The update is free for Patterning 3 owners.  It is not a free upgrade from Patterning 1 or 2.   Apologies for making this unclear.  

- Make sure you are using the same Apple ID on both devices.  

- If you did purchase the Patterning 3 on the iPad, the update is free.  Search for Patterning on the App Store and you should find it, or via http://patterning.app.  

- If it shows a price, you may need to follow through as if you are going to purchase it.  Before it charges you, it should give you a message stating that 'This update is free because you own a previous version of this item. To get this update now, click OK.'  I've heard variations on this, so it may give you a different message, but that's the one I received.  

- As far as I know, only a small number of people (2 or 3?) who own Patterning 3 have been erroneously charged.  If you are charged wrongfully, please reach out to Apple to resolve the issue, and they will refund you. .

I had been collecting information about this bug, but I think I've sent them enough data to work with at this point.  Here is my last update from Apple regarding the bug. (May 5, 2025)

Currently, we do not have an update from the internal team as of yet regarding your issue. I don’t have an estimated time I can provide as each individual issue like these, take time to resolve. 

I would recommend if you have customers who are being double charged, refer them to Apple Care Technical support for refunds if needed. 

You can provide them this information: 

• Online support: https://support.apple.com  
• Telephone support for all regions: https://support.apple.com/HT201232 

Thanks for your patience while Apple resolves this issue.