At the End vs. In the End

Use at the end when talking about an end of something, whether it is physical or metaphorical. Use in the end as a synonym for the adverb finally.

Examples

1. With this option enabled, Veeam Backup & Replication will remove data from backup files on the target backup repository at the end of every synchronization cycle.
2. If there is only one screenshot that illustrates the operation, place it at the end of the topic.
3. In the end, pass the .XML file as the POST body request.