No doubt Google is good at its work i.e. whether it is search engine work or serving advertisements to its clients. The publishers of websites have an opportunity to earn through its Google Adsense program and prospective businesses can get their advertisements listed on Google network through Google Adwords program.
Their is no time limit for an account to get approved with Google Adwords and if you have a business which is legal, they will allow you in their network. However as a caution o not have more than one account for your business and be on the right side of the Google as it can make or break your business.
However their is a restriction in terms of age for Google Adsense account approval and it is six months.