Take a simple action to prepare. During your tenure with any company, maintain a personal accomplishment journal. A journal will work regardless of the type of job you have. A journal will permit you to honor your confidentiality agreements. A journal will give you the information to demonstrate your abilities and skills to prospective employers.
Most people forget the details of the good and varied work that they do, especially over time.
These entries will serve as memory logs when you need them for credentials. They also will take you on a journey of personal growth and insight. Be prudent not to record customer names or computer code. Do not keep proprietary flow charts or any confidential information, data or code. Leave out any specific references to people or customers or management.