In the case of title insurance covering the purchaser, title insurance remains in effect as long as the insured purchaser has title to the land. Some policies also protect those who received title as a result of the purchaser's death, or certain family members (e.g., a spouse or children) to whom the property may have been transferred for a nominal consideration.
In the case of title insurance covering a lender, the policy remains in effect as long as the mortgage remains on title. A lender covered under a title insurance policy is insured in the event the lender realizes on its security and suffers actual loss or damage with respect to a risk covered under the policy. Lenders are usually covered up to the principal amount of the mortgage.
The premium for title insurance is paid once (at the time of purchase). Generally speaking, in Canada the purchaser of the property pays for the title insurance, though there can be situations where the seller pays for it. Some policies automatically cover both the purchaser and lender; others will cover both for a small additional fee.