Metrics install automatically if you have SQL Monitor installed.
If you are using Redgate’s SQL Server monitoring tool, SQL Monitor, you can instantly install and run this metric on your servers.
This metric shows the amount of memory used by cached plans in MB.
Cache memory used (MB)
The amount of memory used by the cache.
The T-SQL query that will collect data
Instances to collect from
Databases to collect from
Use collected or calculated values
Leave the Use a calculated rate of change between collections check box unchecked
An alert for this metric can be added once a baseline has been established.