The policies are generally renewable up to age 70 or later. How they compare in cost to individual plans depends on the amount of health underwriting that is required before they issue you a certificate of coverage. (This is a group policy. As a member of the group, you are issued a certificate.)
If the insurance company issuing the group policy asks you a series of questions about your health or requires a physical exam, you will usually find the premiums to be less costly, assuming you are in good health, rather than a group policy that accepts everyone.
SUGGESTION: If you're not insurable, plans that do not ask any medical questions upfront may be more expensive, but they can be a solution to your life insurance needs. On the other hand, if you're in good health, try to avoid these types of group policies.
IMPORTANT NOTE: Check to see if the policy is convertible to a cash-value life insurance policy, particularly if you think you'll need some form of life insurance throughout retirement. If you're considering converting your group term to cash-value insurance and you're in good health, it pays to shop around. You'll probably be able to find a lower premium and a more competitive policy.