I have two drummers in my neighbourhood. I'm fine because I support that, but I just wonder about the other neighbours, especially those living next door. So far so good, they are still rolling and clashing. Started pretty slow, but now improve quite a lot in about 9 months.
I have never heard of a licence needed for musical insruments in residents. The only licence is for public performances like 7-moon, temple, CCs function and of course HeartRock gigs....up to 10.30pm. 90 db is only a guide, it could be less, somewhere around 65 db I believe. So far the Police will act only on complaints and they don't bother whether the db is 65 or 90. As long as it disturbs the peace of the neighbourhood.
Be nice to your neighbours, be considerate and you'll have less problem.