When playing on a server, the amount of credits you start off with can vary depending on what the admin sets it to. Same thing goes for the amount fo credits you can hold at one time.
How to Make Credits FastEdit
There are two ways to make credits really fast. The first is to mine planets for L4 and L5 minerals for they are the most expensive. Mining asteroids will also prove valuable. The second is to attack Pirates frequently for they drop a lot of valuable items. Pirate stations also have four Plex Storages of items, including valuable L4 and L5 minerals.