When I was 21, I was diagnosed with ADHD. Like many women with Attention Deficit Hyperactivity Disorder, I have the primarily inattentive subtype—or, ADHD that has more symptoms associated with inattention than hyperactivity. Also like many girls and women, I learned to compensate for my ADHD symptoms to the point that it went undiagnosed until my twenties, when I was in university and finally began to truly struggle. ADHD is not just for children: 30 to 60% of children with ADHD continue to experience symptoms into adulthood, and 4.4% of adults have diagnosed ADHD, though the numbers are likely to be much higher. [1, 2]
What are symptoms of Adult ADHD?
It can be difficult to identify adult ADHD because everybody can from time to time experience characteristics that are ADHD symptoms. The frequency and invasiveness of ADHD symptoms are what presents as diagnosable ADHD.
On a regular or continual basis, adults with ADHD experience symptoms that include: 
Disorganization (both in schedule, prioritization, and with objects)
Difficulty managing time and problems multi-tasking
Difficulty focusing on a task and/or completing tasks
Inability to handle frustration, mood swings, or anger issues
Difficulty managing stress
Restlessness or excessive physical movement/activity
Other symptoms or disorders may arise from ADHD, especially if it is not managed effectively. People with ADHD are more likely to experience depression, anxiety affects 50% of ADHDers, and people with ADHD are also more likely to experience addiction (whether to substances or activities, like gambling), substance abuse, psychiatric disorders (such as personality disorders or intermittent explosive disorders), and learning disabilities. 
Most often, a specialist should diagnose ADHD in adults. A combination of testing done by a psychologist and interviews done by a psychiatrist (if medication is a chosen treatment option) is typically done to diagnose ADHD in adults. While not all diagnosed with ADHD have a psychoeducational assessment performed by a psychologist, it is a way to get the big picture of your mental strengths and weaknesses, and gain the best information possible from your assessment. Despite my ADHD diagnosis originally being inconclusive based on my psychoeducational assessment, I learned a lot about my learning strengths and weaknesses which have dramatically improved my life—later, my psychiatrist diagnosed me with severe ADHD, despite testing not completely ruling ADHD in (or out) as a diagnosis.
ADHD treatment goes far beyond medication—although meds can be an important part of treatment for some people (including myself—for whom meds have been life changing!). Learning strategies for organization, emotional regulation, emotional and behavioural therapy, and treating other co-existing disorders are all aspects of ADHD management, and their implementation will vary dependent on the person. Exercise is also an effective non-pharmacotherapeutic intervention for ADHD . Treating ADHD also may mean making lifestyle changes, including those for organization (like installing a key hook so you stop losing your keys!), determining when you do certain tasks best and maximizing on that, and figuring out how you best tackle your to-do list. And yes, fellow ADHDer, you do need to start using a to-do list or planner, whether paper or electronic!
Your experience may vary
ADHD is different for everyone. Whether or not you have co-existing conditions that may make medical ID jewelry a part of your ADHD management plan is dependent on your circumstances. If you do have ADHD and require medical ID jewelry, taking steps to remember to wear it may be necessary! I seldom take mine off (a plus of waterproof medical ID jewelry!) but for others, placing your medical ID bracelet or necklace by (or around!) your toothbrush, or attaching it to your bag or wallet when you remove it may help you remember to wear it, if you experience forgetfulness as a result of ADHD! Another solution that may work for ADHDers is using a medical ID key chain on your keys or wallet, even if it is as a back-up to a bracelet (and pending you don’t forget the item it’s attached to!)