How do I find out what email I used for my account

Rubbot

It’s been 10 years different phone service were I made a google account then switch to a iPhone now I can’t login to the summers market for the free stuff since I don’t know what my email is link to the game

Furrymoosen

You'd have to reach out for support and answer their intense line of identity questions. I imagine that you won't pass, so your only option is probably also not a helpful option.
If you're confident that you know your password, just keep trying emails until one works.