You can apply for a Permanent Residence card if you are a non- EEA National and you have continuously lived in the UK for 5 years as a family member of an EEA national who was a qualified person exercising free movement rights.
It is very important that the full evidence of residence and being a qualified worker for the 5 years is supplied with the application.
You don’t need to apply for a Permanent Residence Card if you’re a EEA national, however, this will be needed in regards to any future application for British Citizenship if that is something that you want to pursue later.