|A Psionicist may have a number of disciplines memorized at one time equal to 2x his rank with this skill, plus standard bonus for KNOW. Thus, a psionicist with an KNOW of 18 and rank 3 in this ability, could have a total of 7 disciplines memorized: 1 for his KNOW of 18 and 2 more for each rank of this ability.|
This doesn't mean that he can't know more, it just means that at any one time he can only have a limited number of disciplines in memory.
Note that the counter discipline for the psionicist's own college do not count against this total. Thus, a psionicist who can have 5 disciplines memorized, can have 5 disciplines , plus both his counter discipline.