1 - go in your library , right click on AS1 , check CD-KEY

CD-KEY may be changed during time so , go in AS1 MP and try to redo the log in procedure using the new CD-KEY



2 - wait for events to pop-up in this group , log in MP using vanilla game (no mods applied yet) and then click on a GSM game , your game should apply the GSM mod without asking you CD-Key