When thinking about having your moles checked it’s important to consider “risk factors”. These are previous amounts of sun exposure, use of sun beds (especially under the age of 18), family History of melanoma or pancreatic cancer and if there is a problem with your immune system. People with more than 50 moles or larger “atypical“ moles are also are higher risk. Previous melanoma increases your risk of a second melanoma. So people with any of these risk factors should be keeping a very careful eye on their moles. Look for change; doubling in size, change in colour, asymmetry are some key changes to watch out for.
A regular dermatologist visit for mole mapping can be reassuring and certainly any moles that are changing should be checked by a dermatologist.
For prevention take precautions in the sun and consider a vitamin D supplement. I recommend checking your whole body every 2 months and asking someone to help check your back. Taking photos is useful. There is a free App Miiskin Skin Tracker that can help you