The phrase "to complete the circle" means to finish or accomplish something that was started or to return to the original point or situation. Full definition
These are designed to be well hidden and require a small task before they are revealed, from completing a circle of stones to picking up a stray plant. (eurogamer.net)
We now complete the circle by looking at P / E changes over the last 120 years. (zeninvestor.org)
I put so much time and a part of myself into my work, meeting and knowing who buys my work completes the circle for me and I am not left hanging. (theabundantartist.com)