UK Permanent Residency
If you have lived legally in the United Kingdom for two to five years, you are eligible to apply to live here permanently, depending on the category of visa you have. Check the appropriate visa category for more information on whether you can apply for permanent residence and the qualifying period for it. The visa category should be there in the Application types for details of categories that may qualify and if your visa category is not listed in Application types, you may not be able to apply for permanent residence.
For UK permanent residency, you need to show that you have enough knowledge of language and life in the United Kingdom.