I am trying for years to get listed

I am trying to get a one very high quality site listed [Business/Financial Services/Offshore Services] since the past 5 years, still no luck.

First i submitted this site 5 years ago, now again i just i tried my luck submitting the link today (will keep trying J).

I am aware it is enough to submit the link just once to dmoz for review.

Do submitted links have expiry time limit until they are resubmitted for review again?

Suggesting your site one more time, as you have done, within a five year period is alright, but further suggestions only serve to risk the site being blocked as spam. Site suggestions do not expire, and offering another suggestion only moves it further down the list, with its new suggestion date so that there is a chance it will take even longer to be reviewed. Please do not continue to suggest the site. A volunteer will eventually review it.

Perfectly clear! Thank you very much ))

So many if someone submit their site 3 times in one month period? Is that spam?

Yes, three times in one month is spam. But likely not enough to get the site banned, although I could be wrong. Patience is key. All editors are volunteers and it can take weeks to years to be reviewed.