If the college is accredited, your credits last forever. But usually most of them count only towards electives, because programs keep changing. If you want federal financial aid, all of your lifetime credits are considered in the total needed to graduate, however- and you can only have so many credits.
I graduated from an ADN program in 2008. Should all of my credits still be good and able to transfer to a BSN program?
As another poster stated it depends upon the particular program.
In theory long as your ADN program was accredited by your state your gen ed credits do not "expire". Nursing courses from a nationally accredited program should be safe as well. The rub comes in what a potential four year program will accept, and that usually falls into two areas; time elasped and content.
Here in the NYC area most ABSN programs have a time limit for how long ago some previous course work could have been taken. This usually refers to but not limited to science and math courses with anywhere from two to seven years on average being the cutoff. So if you took A&P, Micro, and so forth ten or more years ago you probably will have to repeat.