ILR, otherwise known as Settlement or Permanent Residence will allow you to live in the UK indefinitely. It will allow you to leave and return to the UK as you wish, and engage in any type of employment or business. You will no longer have any immigration restrictions. There is no time restriction on your stay in the UK once ILR is approved.
A UK permanent residency visa can be granted once you have been living in the UK for the required time, as indicated below. Eventually you may then apply for British Nationality.
You must spend a number of years in the UK, depending on your immigration status, before you can apply for Permanent Residence.