I invested for 3 years without having my license. You definitely don't NEED it. Having an agent was a great benefit in the beginning. I remember one deal specifically (this was our third deal) where he sent us the listing via text before we even saw it on our own portal. He had already scheduled us a showing because he knew what we wanted. When we were writing up the offer, I wanted to write it for $5k less to "get a deal". The market was just starting to heat up in 2020 and he knew there was risk offering under list price. He essentially put it into perspective for me by saying something along the lines of "is saving $5k worth losing the deal?". At the end of the day, we submitted the offer at full ask, got it accepted, and it's one of the best performing properties that we have now.
On the flip side, about 6 months after that deal, I got my license. In November of 2021 when the market was super hot, we closed on a flip at a great price. I attribute winning that to being able to see the property come up on the MLS immediately, scheduling a showing immediately, submitting an offer immediately, and directly interacting with the agent. There was no middle man and it made the process run super efficiently and fast. A lot of times, speed is the name of the game.
At the end of the day, I think that if you plan on doing deals (even 1 a year), you are someone who can speak well to listing agents, and don't mind doing market research on your own, it's a good idea. I like controlling as much of the situation as possible and not relying on anyone else. As for the cost, I pay less than $1k a year which to me is honestly well worth the control.