I think that each case should be different, especially for long-term clients. For example, when I started 3.5 years ago, I had somebody else pay for my therapy, so I could afford to pay a full 150 euros per session, which is extremely high in my opinion. As the years passed, my T has reduced his fee 3 times (100 euros, 60 euros, and now 40 euros!) instead of increasing it. He reassured me that we wouldn't stop therapy just because I couldn't afford him anymore and asked me how much I could pay, regarding my financial situation. A few weeks ago, I found out that I may be losing my job from September, and he told me that I could see him pro bono and give him the money when I have it. So I don't think that therapists should increase their rates without taking into consideration the situation of each client. My T is very well-off and has many clients that can pay his full-fee, nevertheless he has told me that he has discussed the fee policy from the very first session. In your case, I wouldn't be bothered by the increase, if of course it was a small one and I could afford it, but I would mind not discussing it beforehand and being taken by surprise. I would suggest taking about it during your next session.