Help with

Does anyone know how long any papers submited to Australia house (london) are kept for. I applied for residency about 7 years ago, after waiting nearly 2 years they were going to refuse me because of some mistakes id made on an application a few years earlier whilst in a relationship with an australian. I have since been a resident of New Zealand, that now has expired as I was working in Canada on a skilled work visa. I have a Job Offer from a company in Australia and was wondering if its worth applying atall?
Many thanks with any help anyone can give.