Can having an abortion decrease your chance of conceiving later in life?

NO. No. Very rare to cause any effect. Only if the abortion was infected and complicated by fever etc.
Should Not. It should not. However, complications of the procedure can be infection and scarring of the uterus. And of those occur, which are rare, fertility can be affected.
Generally no. Abortion usually does not cause infertility. However, one of the risks of the procedure for an abortion include uterine scarring, which may subsequently lead to difficulty conceiving. While this risk is low, it is a possibility. If a couple has difficulty conceiving for one year (6 months if woman > 35 years old), an evaluation is warranted.