Hi Tracy! Is this a message you've received or one you're intending to send? No, the grammar is not quite right. You need to add the determiner "which" so it would read, "Thank you for x, y and z *which* have made you valuable members of our company." The intended meaning is that the qualities listed ("high performance, teamwork spirit, devotion and commitment") have resulted in your being a valuable member of the company. I hope that helps.

I agree with Jon, below. I will mention that it is unusual to say 'teamwork spirit." It is understandable but is not good. Instead use "spirit of teamwork."

Jon and Stephanie are correct of course. I have one more thing to add. We would not capitalize "company" as it is not a proper noun. Jon's comment addressed this, but you may not have noticed. I just wanted to draw your attention to it. There is one exception: if for some reason people commonly refer to this company as "the Company" as if that were its proper name. One would in fact even say the word with a slightly different tone in English if one was using it as a proper name.