You can continue using the Pro version for which you have a license.
No.
See Pricing and Other Frequently Asked Questions here.
A Maintenance & Support subscription gives you three great things for one year:
1. License upgrades for major SketchUp Pro releases when they become available. 2. Minor releases which include bug fixes. 3. Access to our technical support resources. Your first year is included when you buy a new license. If you already have a SketchUp Pro license, you can purchase or renew your subscription to get a license for the latest version of SketchUp Pro.