Opera Max made some changes a while back that we weren't super-pleased about, but now it's trying to make amends. Sort of. Opera Max is a free VPN that you're paying for by seeing ads every time you open it to re-enable the VPN. You have to do that every 12 hours, but you can leave it on all the time with the new VIP Mode. However, it shows you lock screen ads when your device is charging.
The ads appear over top of your standard lock screen and include the time, date, and charge level. You have to swipe up to get to the regular lock screen. Again, this only shows up when the device is charging. This is a trade off that I'm sure some people will be willing to make. I'm not sure I would—paying a few bucks for a VPN seems less annoying to me.
If you want to use the new VIP Mode instead of the 12-hour limit, it's in the slide-out navigation menu. The rest of the app works the same as it did previously. No one really wants to look at ads, but in fairness, Opera is running a free VPN for (it claims) over 50 million active users. Gotta pay the bills somehow.