There is no 5 year PR. There is only one PR = permanent residency. That means it's permanent.
The card that indicates that you are a PR of Canada is valid for 5 years. When it's due to expire, you renew it. If it expires and you don't notice, you can still renew it. There is no law that says a PR of Canada needs to have a valid PR card. You only need it for travel and occationally to prove your status.
The only ways to lose PR status in Canada is if you have committed a crime in Canada OR you lied to immigration when you applied and they found out OR you did not meet your residency requirements of staying in Canada at least 730 days over each 5 year period.
Once you live in Canada for 3 years as a PR, you can apply for citizenship. If you meet the requirements of having lived in Canada for a full 1095 days out of the last 4 years before you apply and you have stayed out of trouble, you will be granted citizenship but it takes about a year to get processed.
