I do not know if you resolved this… I was able to solve it deleting the preferences on mac. LIB>pref and deleted the trapcode ones… Also went to the shared folder and deleted the trapcode folder…. and reseted After effects preferences using comm+opt+Shift. while opening the program.
When I tried to install trapcode it showed like a trial and I was able to put our second serial…. it worked like a charm. now we can use our 2 serials.
I hope this helps.