During a school trip, my son slipped and was pulled to safety from a 500 meter fall off of a mountain. When he returned home, my husband had him say the Brachat haGomel blessing after 3 days. I suggested that he take my son to the beit knesset when the Sefer Torah is taken out and say it there, also. He mentioned that one isn’t "Allowed" to say this prayer after 7 days. Is this true? I can’t believe that saying thanks to G-d would only be "allowed" during a time frame.

There is no defined time for Birkat Hagomel, as long as the miracle has its impression. The Shulchan Aruch OC 219:6 writes that one should say within the first three days but Bediavad (if the three days have passed) one may bless after the third day. Rabbi Binyamin Bamberger