tampon complicartions

Hi everyone, 
Today I forgot to change my tampon since this morning.. it's been about 12h (max of hours you can wear a tampon is 8) and I sometimes do this quite often.. (it's because I forget that I have my period) I'm scared that further complications could happen on a long term..
What could be the long/short term circumstances  if you wear tampons for more hours than permited?
Any other advice? Thank you!!!