In Canada, there is no formal limit on the number of terms a prime minister can serve. A prime minister can remain in office as long as they have the confidence of the House of Commons and continue to win elections.
The prime minister is usually the leader of the political party that has the most seats in the House of Commons after a federal election. They can serve multiple terms as long as their party continues to secure a majority or forms a government through coalitions. For instance, notable prime ministers like Pierre Trudeau and Justin Trudeau have served multiple non-consecutive terms.
The primary method for a prime minister to lose their position is through a loss in a federal election or a vote of no confidence from the House of Commons. Therefore, theoretically, a prime minister could serve an indefinite number of terms if they maintain the support of their party and the electorate.