If it's cracked accounts as you mention, there are no grantee for it,
as owner of account may removed you from sharing and change password as easy.
also once sold no grantee that buyer might get hold of the account.
Very risky trade.
Dude, you just need the account the time you download the game, after that you don't need it anymore.
Yes there is a risk but it's minimum and I'm sure the seller will replace the account if it happen..