They switched from per-user licenses to per-computer licenses. I am not sure how this works with previous lifetime licenses.
With my lifetime Arq 5 license I can upgrade to a single computer license with 50% discount and to a 5 computer family pack for 62% discount and I am not sure why the first option is even offered to previous lifetime accounts.
I think the APFS snapshot integration is easily the coolest part of Arq 6. Arq now has access to a special Apple entitlement to take full-desk point-in-time snapshots of an APFS container and backup from that. It's like what time machine would've/should've been, for the cloud.
By the look of their Twitter timeline the launch seems to be a bit of a disaster...
I spent about 15 minutes buying, downloading and installing Arq 6. Then, i spent about 10 hours trying to fix things, and eventually downgrade back to Arq 5 from another backup made with borgbackup...
https://twitter.com/arqbackup/status/1247845283326803968?s=2...
Also, the documentation has been offline all (launch)day: https://www.arqbackup.com/documentation/arq6
It's a shame because i've been hapily using Arq4 and 5 for many years. Hopefully they get their shit sorted quickly.