A quick tip for you to help you retain vocabulary longer:

Write words out using a pen or pencil that you really like.

For example, a nice Japanese mechanical pencil (I like my Kuru Toga) or a fountain pen (for example, a Lamy) with sea blue ink.

You might find that you enjoy tracing the curves of the letters or looking at the finished word. All this will help the word make its way into your long-term memory.