Max sessions 150/year. Love https://www.fastsupport.com/ from logmein.com but that's probably an expensive subscription for high volume users.
I subscribe to TeamViewer for extended remote access purposes. Fine for that but not good for quick support calls with my few non tecch saavy clients.
Spent close to an hour the other day with one person just getting them to install TeamViewer. The kept clicking on the TeamViewer web site install button thinking that would start the remote session. Then they couldn't find where they had downloaded the install file. etc etc.
Len Raphael
Oakland CA