Cracked software is modified code. There is no guarantee that your backups will be consistent or restorable when you actually need them.
Many "activators" are actually Trojans. Once executed with administrative privileges (required for backup software), they can encrypt your entire server or create backdoors for hackers. Cracked software is modified code
Veeam is actually very generous with its official free versions, making a crack completely unnecessary for many users: Cracked software is modified code