128 Character Password Strings Support?

Is there a way to get Only Key to hold passwords up the SHA512 string length of 128 characters?

No but there is a work around which requires you to split the password into three, you need to add by addiing part to the URL box, then part in the username box and then the final part in the password box, and make sure not to select tab or return after input (this allows up to 168 charator length)