Unity Technologies revealed that the team will increase prices in 2020.
Currently, a Plus license costs users $35 per month, while a Pro license costs $125 per month. Starting January 1, 2020, a Plus license will cost $40 per month and a Pro license will cost $150. This will be the first price increase since 2016. Please note that if you're a free user, you can relax - there are no changes to the Personal edition.
"Effective January 1, 2020 at 12:00 am UTC, the price for Unity Pro subscriptions will be USD $150/month and Unity Plus subscriptions will be USD $40/month," wrote the team. "This pricing applies to new subscriptions, additional seats, and renewals of expiring custom agreements. Current seat subscriptions and current custom agreements are unaffected."
You can get more details here.