I don't know how big your company is, but does it provide employees with a written travel policy? If so, is your situation covered in it or is your boss taking some "poetic license"?

If there is a travel policy that says "this is how it's done" and your boss is following it - then s/he really isn't stealing anything.

If there isn't a policy, or if the policy is nonspecific on how loyalty program perquisites are handled - then maybe you have grounds to enter into a dialogue to get what you want (or at least have the policy clarified).

All that said, with all due respect I agree with what pauleeepaul advised.