Good paste on a healthy cooler can last years. You do not need a calendar reminder every twelve months if the machine runs cool and quiet.
Think about a re-paste when temps have crept up over time, you have taken the cooler off, or you are already deep cleaning and the old paste looks dry or patchy.
Done badly (too much paste, uneven mount) it can make things worse. Not confident? A service visit is cheaper than a cooked CPU. Happy to help around the Midlands.
Not sure what you need?
Pick a path, run Find my PC, or message with your games and budget. We will keep it practical.