Consequence of not having PAN
PAN is not restricted to people who are above the age of 18 or citizens of India. Every individual who has a source of income and files income-tax returns or intends to enter financial transactions in India requires PAN. So a foreign national living and working in India and earning a taxable income needs to acquire PAN. Similarly, a child artist whose annual income is taxable also needs a PAN.
If you do not furnish PAN, then tax is deducted at a much higher rate. For instance, if the annual interest you earn on your bank fixed deposits is at least Rs10,000, then banks deduct tax at source before crediting the interest to your account. Tax will be charged at 10% if you produce PAN but flat 20% or higher if you do not give PAN.
You can acquire PAN only once and PAN will remain the same throughout your life, irrespective of whether you change jobs or cities. If, however, you lose the card, you will be issued a new card but the number will remain the same.