In legal practice, retainers are common practice. You reserve a service because you are certain you will be using it regularly. 

What does a retainer with me entail? An all-inclusive service for people who know what they are worth. What they need. For example a confidant to get them through a difficult time. The security of knowing that someone is having their back.

∙ Guaranteed same-day call back
∙ Guaranteed same day treatment 
∙ Fixed date for energy clearing every 2 weeks

Your further contingent depends on the details of the retainer.