Is it worthy an ef 24-70mm f2.8l ii usm at the place of the ef-m 18-55?

Hi!

I have the possibility to buy a used ef 24-70mm f2.8L ii usm for 1042$ from a professional photographer. I haven't seen yet the lens. He said to me that the lens is recently servised by Canon and its something he does with all his equipment because they are the instruments of his job. If you see my photos I mostly take people, old buildings, old man made objects, architecture if there is a good occasion also portraits. I have only the ef-m 18-55 and most of my photos are near the 55mm side. I quite often find the low light being a problem even if I like taking photos under these conditions. I use this combo 3 years and I am quite happy with the results. I don't have experience with better lenses so I don't know what better look a better lens would give to my photos and most important if it is worthing the expense for these difference in results. I definitely don't want a collection of lenses, one for each photo occasion. I don't feel also comfortable with the idea to spend money on ef-m lenses since I always "dream" to go full frame. So looking different lenses, zooms and primes, from the ef-s 55-250, ef 70-200mm, ef 100mm, 135,ecc, recently I had the possibility to buy the ef 24-70mm f2.8L ii usm like I said in the beginning. I would like to know (and that's why I wrote all this information) a few opinions on the cost, if it's worthing for an amateur photographer, and in general what are your thoughts. Please concentrate on the lens mostly. I know that Eos-m3 is an old camera but I already said that I don't want to make a collection.

Thank you in advance.