What nationality are you?
You will need to submit an application for permanent residence.
You will need to prove that you have been exercising treaty rights for at least 5 years preceding the date of application.
You will need to to provide documents such as:
Pay slips, P60's, Bank Statements, Evidence of where you have been living, details of any family members, photographs, correspondence from the last 5 years, this can be a few letters from each year.
I hope this answers your question. If so, kindly rate the answer and provide feedback.
If you have any further questions, please do not hesitate to ask.