A golden premium member can play 10, diamond and platinum ones as many as they want. The others one only. But the above doesn`t apply when it comes to the official Chess.com tournaments - all members are allowed to play them all. Consequently, you can play all the official tournaments + 1 created by someone else.
Tournaments, how many can I be in at one time?

To add to what Boletus_CZ said, I don't think you can accidentally exceed the allowed number of current numbers. You just won't be able to join new ones when you've reached the limit.
Have entered two recently.. if I do not get myself out of one.. will I be exceeding the limit? Any info would be greatly appreciated!