I paid a guy to flash my 0225u drive. He just dumped the key of the drive(he did not press the 'read' button to dump the full original firmware as asked by jf tutorial.), then spoofed the key to lt3.0 CFW and wrote the drive.
The drive read disks well now, but I wonder if the cfw in my drive is as good as one made from a full original firmware. If it's not, will it cause a live-ban?
Now I have only the dvd key of my drive. I don't have a full original firmware. Will this be a problem in future update or something?
Thanks.

I think you're talking about dummy.bin not only the DVD key, if the drive read original & backups, it's OK, don't care about.
save your dummy & LT plus 3.0 in some place, you'll need the one day.

I'm even not sure it is a dummy.bin, since he renamed it. I loaded the bin file into jungleflasher, and it showed the firmware type is 'slimkey extract' .
it do read original & backups well. I just have a little bit concern about the live-safety and future trouble.
jungleflasher shows:
Inquiry string found
Identify string found
Drive key @ 0xA030 2XXXXXXXXXXXXXXXXXDC
Firmware Osig: [PLDS DG-16D4S 0225]
Firmware is: SlimKey Extract

BTW, in jungle flasher tutorial, after writting the drive, there is a step 'restoring sector 0x3E000'. What does it do? What information is in sector 0x3E000?

NO this wont be a problem. Your drive wroks now obviously and he made the CFW from that dummy.bin slimkey extract, so you are fine.