[@Robert]
Hi Robert,
This complimentary subscription is valid for one year. However, the product offers a free version for personal use, which is valid for lifetime. If you intend to use the lifetime free subscription, go ahead and sign up here https://www.zoho.com/vault/ . You will be initially enrolled to a 15-day free trial of the Enterprise edition. At the end of the 15-day period, it will automatically turn into the free plan.
Thanks,
Bala