There is not a lot to go on from your initial post so the first thing to check is if it is present under 'Tools', 'Add-ins'. If it is then turn it on and start using it under the 'Motion Study' tab at the bottom of your screen.
Otherwise, assuming that your license has access to Motion there are a few things that might be causing you to not see the Motion add-in.
It might not be installed. To check you would want to do the following to make sure you have Motion installed:
- Go to the Windows Control Panel
- Go to "Features and Program"
- Locate the SolidWorks installation in the list of program and elect to "Change" it
- Select "Modify the individual installation" and proceed next
- Do not modify anything on the serial number screen and proceed ‘Next’ to the ‘Product Selection’ screen
- On the ‘Product Selection’ make sure 'Motion' is present and turned on (like you see below)
If it installed there (present and checked) then first cancel out of modifying your install and apply this fix (GoEngineer - KB3072630 Repair). If your install doesn't show Motion as being installed (present and not checked or not present at all) cancel out of modifying your install and apply this fix (GoEngineer - KB3072630 Repair) then modify the installation to include 'Motion'.
Please make a call to your SOLIDWORKS reseller for activation issue.