Track every GCal event you're invited to in a Google spreadsheet -

Connect

An easy archive of every meeting you're invited to you for the Google Calendar you select.

If

You respond to an event invite

The trigger fires every time you respond to an event you're invited to. Note: The time in the ingredient will be based on the timezone set in Google Calendar.

Then

Add row to spreadsheet

This action will add a single row to the bottom of the first worksheet of a spreadsheet you specify. Note: a new spreadsheet is created after 2000 rows.