Why my doctor put tapes on on my upper stitches?

That is to say, there is not particular reason.  On the other hand, some surgeon close the eyelid incision with what is called a subcuticular stitch.  The actual ends of the suture are stabilized with the tape rather than a knot.  It is quite possible that the paper work you were given by your surgeon's office discusses the tape, why it is there, and when it will be removed.  So take a look.  If you still can not figure it out, call your surgeon and discuss the matter.

 Placing tape on the eyelids after blepharoplasty is sometimes chosen by the plastic surgeon. This might be to reinforce the incision or support the position of the lower lid.

Some surgeons use tape (or steri-strips) on the incision sites to prevent the wound from opening and to minimize scarring.  Since I don't usually use tape since I don't find it to be helpful, I would recommend that you ask your surgeon for their expertise.  In most cases, it will fall off or be removed within a few days after surgery.  Best of luck!