+1 to Milandro, could be you're not taking in enough mouthpiece. Fix simple before going advanced
A kind of offbeat and odd technique, but just through learning my overtones, high altissimo (without biting), and circular breathing my embouchure became very, very strong. I used to get tired and would have to pull the horn off my face and pull and stretch my lips a little to get them feeling better.
I think a lot of it will be fixed within the practice room by practicing longer and practicing some of the things above. Play your overtone series on Bb-D chromatically and hold out each note of the series as long as you can. When you reach the altissimo level overtones you will probably start to feel some fatigue in your embouchure muscles, especially when holding them for an extended period of time. But you will learn a lot of control and better intonation, plus you'll get pretty good at altissimo.
If you delve into circular breathing at all, try to go for about 3 minutes on a C#2 (non-overtone; just open) and because of your cheeks being puffed out and the contracting of your embouchure when taking a breath you will get extremely tired. Just keep working at it. The 3 minutes is a goal and it is not expected you should be able to go anywhere close to that when you start.
Also practice some pieces with a lot of octave changes. There's a piece of music out there that is the Prelude to Bach's Cello Suite No.1 that starts on D and it is perfect for saxophone as it has no altissimo and whatever notes run into a range below that of the instrument just take up an octave.
This song is great because of the octave changes and you have to have a good embouchure to play it, try to play the majority of it slurring (take breaths when needed as circular breathing during octave changes is rather difficult).
Another 2 exercises (found in the tone production area) include: playing strictly on your mouthpiece, overtone octave slurs.
For the mouthpiece try to start as low as you can play on the mouthpiece (using throat, embouchure, and air pressure) and try to play chromatically up to as high as you can go. Then after you get good enough try to play some scales (probably won't get much more than an octave or the full scale at all), then proceed to arpeggios and eventually simple tunes.
For the overtone slurring play an F2 without the octave and try to perfectly slur between F2 and F1 without any note bending. Proceed down to Bb
If you work these into your practice routine (along with practicing for extended periods of time and some fast jazz licks or whatever you want to work on), your embouchure should become strong as admantium, and your problem should disappear, or only become present after 3,4,5+hours.
Hope this helps, sorry for the length just trying to get everything out there that will help.