I forgot the Google account name that I used for buying apps on Google Play, can I recover it somehow?
In my opinion you should search for devices that you might had linked that account and check if someone has that email address. Think if you ever sent a email using that account to a close friend, family member or other internet service. 

You can also take a look at this forum answer: https://productforums.google.com/forum/#!msg/gmail/ydNElvUjJVU/hNjOMBN0dNYJ