If you acquired an employment in Pakistan, keep in mind that you also need a work visa. This visa allows its holder to stay in Pakistan for 1 year and take up employment within the country. During this period, you can exit and re-enter the country. Also, you can extend your work visa every year.
How to apply for a work visa in Pakistan
Your work visa application will be first sent to the Directorate General of Immigration and later to the Ministry of Interior for authorization.
When applying you also need a corporate sponsor for the letter of approval to the immigration authorities. It usually takes up to 3-4 weeks to get ahold of a work visa in Pakistan and you will receive it at your closest Pakistan embassy abroad.