Clubs are divided into 3 grades: Common, Rare, and Epic.
The maximum level differs according to the club's grade.
Common Clubs can be upgraded to level 10, Rare Clubs to level 8, and Epic Clubs to level 7.
Lower grades don't necessarily mean that the stats on the clubs are lower!
Compare and check out various different type of clubs you acquire to find the right one that fits your play style.