Now it is in your working memory. But if you want to recruit it to become a part of your long-term storage you have to -- yep, repeat it...and repeat it...during the next 60 to 120 minutes.
Are you seeing a pattern here? For new information to become a part of you, you need to repeat it. Maybe it's the doctor's address or a shopping list (with seven items on it, of course) or a piano piece you are learning. Repetition will help cement that into your memory. According to the Brain Rules website, "It takes years to consolidate a memory. Not minutes, hours, or days but years. What you learn in first grade is not completely formed until your sophomore year in high school."
Don't be discouraged. Choose something do-able, like a telephone number, and repeat it several times over a 30-second period. During the next couple of hours, repeat it several more times. Then go make a call and tell your friend how easy it was to memorize his or her number! If you hope to keep that memory alive, though, avoid adding it to your speed dial!