How can i find out which Apple ID was used to download my copy of Logic Pro X?

Hi,

I've bought an IMac several months ago, and downloaded Logic Pro X from the App Store. Now i got a Macbook Pro and i'd like to install Logic on that too, but apparently i didn't purchase Logic using my usual Apple ID, as it doesn't appear in the "Purchased" apps. I've tried already all of the accounts i have access too, but i can't find my Logic Pro X anywhere! Obviously, not knowing which email address i've used i can't find the receipt, i only can provide the payement details as it was done with my credit card. When i got Logic i had never used a Mac before, nor the App Store and i didn't have a clue how Apple ID's worked, i might5 have created a different account just to buy Logic and then forget all about it..any ideas on how to find out how the app was purchased?

Thank you!