Hey Nikks,
WORM - when your WORM is full, therse no option to start from scratch with this tape, it’s full, not overwritable and ready for keeping the rest of it’s life in a safe :-)
Tape protection - defined within Veeam. It will not be able to append new data on it, it’s not possible to erase or remove data from it (only when your protection is removed)
Retention period - as with other Backup media, if it’s within retention, this media cannot be overwritten or deleted. Append ius possible (if defined in the job/pool). After the defined Retention, this tape can be “reused”.
So based on your request, normal tapes (not WORM) with normal reteion period should be your way to go.
Hope it’s getting more clear now.