Is a vasectomy still effective years after it was performed?

Yes. There have been a couple of very rare cases where a vasectomy has not been permanent due to the man's severed tubes "reconnecting" by forming a new path - nature overcoming! But these cases are very rare compared to the vast number of vasectomies performed. After having the procedure, you should've been tested - about a month later - to make sure it was successful. After this time you should consider yourself sterile.