Finally, At last or In the end

Finally introduces the last part of a list. It can also suggest that something has happened after a long wait.
At last suggests something has happened after a long and annoying wait.
In the end suggests something has happened after a lot of changes.

• First, we must improve our sales. Second, we must reduce the number of complaints. And finally, we must improve our customer service.
• I have finally found a job.
• At last they have repaired my car.
• I tried on three different shirts. In the end, I bought the blue one.