You simply match the period of time you'll need life insurance coverage to the available rate guarantee period. Most insurance carriers offer term coverage for a period of 10, 15, 20 or 30 years of protection with level premiums.
For example, if your children are young or you have decades to go on your home mortgage loan, look at 20 or 30 year term life policies.
If your children are leaving the nest and your home is paid off or nearly paid off, perhaps a 10 or 15 year term life insurance plan might meet your needs.
Also, some term life policies allow for an option of renewability. You may renew your term life insurance for another term (usually up to 10 years) if you decide you need life insurance for a longer term than your initial life insurance term.
Learn more about level term life insurance coverage and how it works.