The retain operation stores a TrustedForm certificate in your account per your account retention setting
(defaults to 5 years). This should be performed for all certificates associated with leads you intend to contact
so that you have proof of the events that took place.
Important: When retaining a certificate, you must also execute the match_lead operation. This ensures that the lead with
which you received the certificate matches the lead data collected on the cert.
Requires a Self-Service plan or higher.
