The company doesn't have to keep the paid up capital in the bankaccount. Off course it can do business with the money.
But there are some regulations to make sure that the capital of the compnay doesn't 'disappear' without a serious explanation.
When something is payed with money of the company, something else will have to come in return, e.g. if you buy a computer, the company will own the computer and that computer must be usefull for the business in which the company is involved.
It is possible to establish another company with the paid up capital. Then the shares of the new company will be owned by the first company.