PR is acquired automatically after 5 years of exercising treaty rights however you may find it useful to apply for confirmation that you have acquired PR for your partner's application.
Given that you are likely to have acquired PR, and are therefore 'settled' in the UK you and your partner can choose whether you want to go down the Immigration Rules route (currently settlement after two years -although this may change soon, evidentially more laborious, need to meet maintenance and accommodation requirements, more expensive in terms of application fees), or under the EEA Regs (application free, arguably less evidence needed although given that you are unmarried substantial evidence of your relationship and in particular evidence of cohabitation will be required - as it will be for the immigration rules route), no requirement to meet minimum maintenance and accommodation thresholds, but settlement takes 5 years.
Have a look in the EEA applications section of the forum for info on the EEA regs route. Look in this section for info on the immigration rules route.
How long have the two of you been together? How long have you been living together? What's your partners current immigration status?
See
guidance for the immigration rules route
See
guidance for the EEA regulations route
